Local OfficeSan Francisco, CA 94120-7880Doc No.10649396v2Doc
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Name10649396_2.DOCAddressee(s) Signer(s) Cause No. Parties Client
No.086666Matter No.0000001Client Name Matter Name Caption Bank Document Caption
Client Name Caption Opp Counsel Client Name Caption Attorneys for Caption Opp
Counsel for Document Management LibrarySan_FranciscoRecipient Array
_AdHocReviewCycleID204629240_EmailSubject_AuthorEmailsawad@PillsburyWinthrop.com
_AuthorEmailDisplayNameAwad,
Suzanne 10649396v2 3499_1




                                POWER OF ATTORNEY

         I do hereby constitute and appoint John H. McGuckin, Jr., Morris W.
Hirsch, and Vicki Wilderman, each individually, with full power of substitution,
as my true and lawful attorney-in-fact to:

         (1) sign and file on my behalf any and all Forms 3, 4 and 5 (including
any amendments) as may be required to be filed with the U.S. Securities and
Exchange Commission under Section 16 of the Securities Exchange Act and any
stock exchange or similar authority as a result of my ownership of or
transactions in securities of UnionBanCal Corporation (the "Company"); and

         (2) take any other action of any type whatsoever which, in the opinion
of such attorney-in-fact, may be necessary or desirable to complete, sign or
file with the relevant authorities any such Form 3, 4 or 5, or any amendments,
or otherwise of benefit to me or in my best interest, or legally required,
including filing the Form ID, in connection with the foregoing.

This Power of Attorney shall remain in full force and effect until I am no
longer required to file Forms 3, 4 and 5 with regard to my ownership of or
transactions in securities of the Company, unless I earlier revoke it in
writing.

I hereby ratify, approve and confirm all that any such attorney-in-fact, or any
substitute, may lawfully do and cause to be done by virtue of this Power of
Attorney.

I hereby acknowledge that John H. McGuckin, Jr., Morris W. Hirsch, and Vicki
Wilderman are not assuming, nor is the Company assuming, any of my
responsibilities to comply with Section 16 of the Securities Exchange Act.


                                                     /s/ Masashi Oka

                               Date: June 20, 2005