PLEDGE AGREEMENT

          THIS PLEDGE AGREEMENT ("Agreement"), dated as of the 31st day of July,
1997, is entered into by and between MOBILE MINI,  INC., a Delaware  corporation
(the "Company"),  and ARIZONA LAND INCOME  CORPORATION,  an Arizona  corporation
(the "Lender").

                                    RECITALS:
                                    --------

          A.  The  Company  and  the  Lender  have   entered  into  a  financing
transaction  pursuant to which the  Company has  executed  that  certain  Senior
Subordinated  Promissory  Note dated July 31, 1997 (the  "Note") in favor of the
Lender.  All capitalized  terms used as defined terms in this Agreement,  unless
otherwise  expressly  provided  herein,  shall have the meaning set forth in the
Note.

          B.  Pursuant  to the Note,  the  Company  has agreed to  establish  an
interest  reserve  account (the "Reserve  Account") and to grant to the Lender a
security  interest  in such  Reserve  Account to secure all  obligations  of the
Company arising under the Note in accordance with the terms of this Agreement.

                                   AGREEMENTS:
                                   ----------

     NOW,  THEREFORE,  in  consideration  of the  premises  and  other  good and
valuable  consideration,  the receipt and legal  sufficiency of which are hereby
acknowledged, the Company and the Lender agree as follows:

I. Security  Interest.  The Company  hereby pledges and grants to the Lender and
its  successors and assigns a security  interest in all of the Company's  right,
title and interest in and to all of the following: (i) the Reserve Account which
has  been  established  at Bank One  Arizona,  N.A.  (the  "Bank"),  as  further
identified  on  Exhibit  A  attached  hereto,  and (ii) any and all funds of the
Company   deposited   therein   and  any   earnings   therefrom   (collectively,
"Collateral"); provided, that so long as no Event of Default shall have occurred
and be  continuing,  the Company shall be entitled to retain for its own account
any interest  earned on the Reserve  Account.  Without  limiting  the  foregoing
pledge and grant of security  interest,  and  regardless  of whether an Event of
Default (as defined in the Note) shall have occurred and be continuing,  so long
as the Note is  outstanding,  the Company  shall be  permitted  to use any funds
constituting  the  Collateral  only to pay interest  under the Note as set forth
therein.  The Company shall promptly  provide notice of the foregoing pledge and
security  interest to the Bank, in such form as is reasonably  acceptable to the
Lender, and shall obtain the acknowledgement of the Bank of the terms thereof.

II.      Indebtedness Secured.
         --------------------

 
     A. Description of  Indebtedness.  This Agreement is made for the purpose of
securing the following:

          1. payment of the principal  amount of the Note,  together with unpaid
interest, and any extension, modification, substitution or renewal thereof; and

          2. performance of any and all other obligations of the Company arising
under the Note.

     B. Pledge Obligations.  The term "Pledge  Obligations" as used herein shall
mean, collectively,  the monetary, performance and other obligations at any time
secured hereby.

III. Representations and Warranties. The Company represents and warrants and, so
long as any Pledge Obligations remain unpaid or unperformed,  shall continuously
represent and warrant that:  (i) each  instrument  or document  constituting  or
evidencing ownership of the Collateral is genuine and is in all respects what it
purports  to be;  (ii) the  Company is the owner of the  Collateral  free of all
security  interests or other  encumbrances  other than those granted pursuant to
this  Agreement  in favor of the Lender,  and no effective  financing  statement
covering the  Collateral  has been filed or recorded in any public  office other
than those filed or recorded  pursuant to this Agreement in favor of the Lender;
(iii) the  Company  is  authorized  to enter into this  Agreement;  and (iv) the
security  interest granted to the Lender pursuant to this Agreement with respect
to all  amounts  held in the  Reserve  Account  is a first  and  prior  security
interest in such Collateral.

IV. Affirmative Covenants.  So long as any Pledge Obligations remain unpaid, the
Company will defend the  Collateral  against the claims and demands of all other
parties,  will keep the  Collateral  free from all  security  interests or other
encumbrances  other  than the  Lender's,  and will not sell,  transfer,  assign,
deliver or otherwise  dispose of any of the  Collateral or any interest  therein
other than in  accordance  with the terms of the Note without the prior  written
consent of the Lender.

V.  Remedies.  In the event of any Event of Default  under the Note arising as a
result of the Company's failure to pay when due any interest  thereunder and the
Company's  failure to cure such  default  within ten (10) days after  receipt of
written notice thereof  (stating that a failure to cure such default will result
in the  application of the  Collateral to the payment of  obligations  under the
Note),  the  Lender  shall  have  the  right  to  apply  all or any  part of the
Collateral to payment of interest due under the Note. After such application and
provided the obligations of the Company hereunder have been fully satisfied, the
Lender  shall hold the balance of the  Collateral  (if any) for  disposal by the
Company or such other person as is entitled  thereto by law.  The Company  shall
remain liable for any and all of its obligations  hereunder or under the Note in
excess of any amount so applied.

VI. Miscellaneous.
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                                       2

          A.  Waivers.  No waiver by the Lender of any of its rights or remedies
hereunder or otherwise  shall be  considered a waiver of any other or subsequent
right or  remedy  of the  Lender;  no  delay  or  omission  in the  exercise  or
enforcement by the Lender of any rights or remedies shall ever be construed as a
waiver of any right or remedy of the Lender;  and no exercise or  enforcement of
any such right or remedy  shall  ever be held to exhaust  any right or remedy of
the Lender.

          B.  Preservation  of  Security  Interest.  The  Lender  shall  have no
obligation  to take,  and the  Company  shall have the sole  responsibility  for
taking,  any and all steps to preserve the Lender's  rights  against any and all
other parties with respect to the Collateral.

          C. Binding  Effect,  Assignment and Entire  Agreement.  This Agreement
shall  inure to the  benefit  of,  and shall be  binding  upon,  the  respective
successors and assigns of the parties hereto. The Company has no right to assign
any of its rights or obligations  hereunder without the prior written consent of
the Lender.  This Agreement,  and the documents  executed and delivered pursuant
hereto,  constitute the entire agreement between the parties, and may be amended
or modified only by a writing signed on behalf of each party.

          D. Governing Law. This Agreement and the transaction  evidenced hereby
shall be governed by the laws of the State of Arizona (without  reference to the
provisions thereof relating to conflicts of laws).

          E.  Notice.  Whenever  it is  provided  herein  that  notice,  demand,
request,  consent,  approval or other communication shall or may be given to, or
served upon,  any of the parties,  or whenever any of the parties hereto desires
to give or serve upon the other any notice, demand, request,  consent,  approval
or other communication with respect hereto, each such notice,  demand,  request,
consent,  approval  or other  communication  shall be in  writing  and  shall be
effective for any purpose only if given or served by (a) certified or registered
U.S. Mail, postage prepaid,  return receipt required, (b) personal delivery with
a signed  receipt or (c) a recognized  national  courier  service,  addressed as
follows:

          If to the Company:                 MOBILE MINI, INC.
                                             1834 West Third Street
                                             Tempe, Arizona  85281
                                             Attn:  Lawrence Trachtenberg



          If to the Lender:                  ARIZONA LAND INCOME CORPORATION
                                             2999 North 44th Street, Suite 100
                                             Phoenix, Arizona  85018
                                             Attn:  Tom Hislop
                                       3

Any such notice may be given, in the manner provided in this Section,  on either
party's  behalf by its attorneys  designated by such party by notice  hereunder.
Every notice given hereunder  shall be effective on the date actually  received,
as indicated on the receipt  therefor or on the date delivery thereof is refused
by the recipient thereof.  Any party hereto may by notice delivered to the other
parties, change its address for purposes of this Agreement.

     F. Expenses.  The Company shall pay all costs and expenses  incurred by the
Lender  in  enforcing  this  Agreement  and in  realizing  upon the  Collateral,
including,  without  limitation,  if the  Lender  retains  counsel  for any such
purpose, its reasonable attorneys' fees and expenses actually incurred.

     G.  Counterparts.  This Agreement may be executed in counterparts,  each of
which shall be an original but all of which  together  shall  constitute one and
the same Agreement.

     IN WITNESS  WHEREOF,  the parties hereto have executed this Agreement as of
the date first set forth above.

          "the Company"                     MOBILE MINI, INC.
                                            a Delaware corporation


                                            By:________________________________
                                            Name:______________________________
                                            Title:_____________________________



          "the Lender"              ARIZONA LAND INCOME CORPORATION, an
                                            Arizona corporation


                                            By:________________________________
                                            Name:______________________________
                                            Title:_____________________________

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                                    Exhibit A

                                 RESERVE ACCOUNT


                  Account No. 4003-8927 at

                           Bank One
                           ABA # 1221-00024
                           44 West Broadway Road
                           Tempe, AZ 85285

                                    Exhibit B

                                NOTICE OF PLEDGE

                                 (see attached)