CERTIFICATION


I, Martin A. White, certify that:

  1. I have reviewed this quarterly report on Form 10-Q of MDU
     Resources Group, Inc.;

  2. Based on my knowledge, this report does not contain any untrue
     statement of a material fact or omit to state a material fact
     necessary to make the statements made, in light of the
     circumstances under which such statements were made, not
     misleading with respect to the period covered by this report;

  3. Based on my knowledge, the financial statements, and other
     financial information included in this report, fairly present in
     all material respects the financial condition, results of
     operations and cash flows of the registrant as of, and for, the
     periods presented in this report;

  4. The registrant's other certifying officer and I are responsible
     for establishing and maintaining disclosure controls and
     procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-
     15(e)) and internal control over financial reporting (as defined
     in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
     registrant and have:

       (a) Designed such disclosure controls and procedures, or
           caused such disclosure controls and procedures to be designed
           under our supervision, to ensure that material information
           relating to the registrant, including its consolidated
           subsidiaries, is made known to us by others within those
           entities, particularly during the period in which this report
           is being prepared;

       (b) Designed such internal control over financial reporting,
           or caused such internal control over financial reporting to
           be designed under our supervision, to provide reasonable
           assurance regarding the reliability of financial reporting
           and the preparation of financial statements for external
           purposes in accordance with generally accepted accounting
           principles;

       (c) Evaluated the effectiveness of the registrant's
           disclosure controls and procedures and presented in this
           report our conclusions about the effectiveness of the
           disclosure controls and procedures, as of the end of the
           period covered by this report based on such evaluation; and

       (d) Disclosed in this report any change in the registrant's
           internal control over financial reporting that occurred
           during the registrant's most recent fiscal quarter (the
           registrant's fourth fiscal quarter in the case of an annual
           report) that has materially affected, or is reasonably likely
           to materially affect, the registrant's internal control over
           financial reporting; and

  5. The registrant's other certifying officer and I have disclosed,
     based on our most recent evaluation of internal control over
     financial reporting, to the registrant's auditors and the audit
     committee of the registrant's board of directors (or persons
     performing the equivalent functions):

       (a) All significant deficiencies and material weaknesses in
           the design or operation of internal control over financial
           reporting which are reasonably likely to adversely affect the
           registrant's ability to record, process, summarize and report
           financial information; and

       (b) Any fraud, whether or not material, that involves
           management or other employees who have a significant role in
           the registrant's internal control over financial reporting.

Date:  August 3, 2005


/s/ Martin A. White
Martin A. White
Chairman of the Board
 and Chief Executive Officer