<Page>

                                                                      Exhibit 24

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Janet M. Dolan
                                        ----------------------------------------
                                                    Janet M. Dolan

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ David C. Cox
                                        ----------------------------------------
                                                    David C. Cox

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Andrew P. Czajkowski
                                        ----------------------------------------
                                                    Andrew P. Czajkowski

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ James T. Hale
                                        ----------------------------------------
                                                    James T. Hale

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Pamela K. Knous
                                        ----------------------------------------
                                                    Pamela K. Knous

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ William I. Miller
                                        ----------------------------------------
                                                    William I. Miller

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Edwin L. Russell
                                        ----------------------------------------
                                                    Edwin L. Russell

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Stephen G. Shank
                                        ----------------------------------------
                                                    Stephen G. Shank

<Page>

                                 TENNANT COMPANY

                                Power of Attorney
                           of Director and/or Officer

     The undersigned director and/or officer of Tennant Company, a Minnesota
corporation, does hereby make, constitute and appoint Janet M. Dolan, Anthony T.
Brausen and James J. Seifert, and each or any one of them, his or her true and
lawful attorneys-in-fact, with power of substitution, for the undersigned and in
his or her name, place and stead, to sign and affix the undersigned's name as
director and/or officer of the Company to a Registration Statement or
Registration Statements, on Form S-8 or other applicable form, and all
amendments (including post-effective amendments) thereto, to be filed by the
Company with the Securities and Exchange Commission, in connection with the
registration under the Securities Act of 1933, as amended, of shares of Common
Stock or other securities proposed to be issued or sold by the Company pursuant
to the Tennant Company 1998 Management Incentive Plan and the Tennant Company
Restricted Stock Plan for Nonemployee Directors, and to file the same with the
SEC, granting unto these attorneys-in-fact, and each of them, full power and
authority to do and perform any and all acts necessary or incidental to the
performance and execution of the powers herein expressly granted.

     IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 21st day
of February, 2002.

                                               /s/ Frank L. Sims
                                        ----------------------------------------
                                                    Frank L. Sims