FIRST AMENDMENT AGREEMENT


                  THIS FIRST AMENDMENT AGREEMENT (this "Amendment"),  is entered
into  as  of  November  25,  1996,  between  Komag,  Incorporated,   a  Delaware
corporation  (the  "Borrower"),  and The  Dai-Ichi  Kangyo  Bank,  Limited  (the
"Lender").

                  WHEREAS,  the  Borrower and the Lender are parties to a Credit
Agreement dated as of October 7, 1996 (the "Agreement");

                  WHEREAS, the Borrower has requested that the Lender agree to a
certain  amendment to the  Agreement  and the Lender has agreed to such request,
subject to the terms and conditions hereof;

                  NOW,  THEREFORE,  in consideration  of the mutual  agreements,
provisions and covenants contained herein, the parties hereto agree as follows:

                  1.  Definitions.  All capitalized terms used in this Amendment
(including in the recitals  hereof) and not otherwise  defined herein shall have
the meanings assigned to them in the Agreement.

                  2.  Amendment  to  the  Agreement.  In  Section  1.01  of  the
Agreement,  the definition of  "Borrower's  Account" is amended by inserting the
phrase "with the number 12336-23191 that is maintained by the Borrower with Bank
of America NT & SA at GPO-Account  Administration-5693,  1850 Gateway Boulevard,
8th Floor, Concord, CA 94520 (with wire payments to be made for credit to Komag,
Incorporated,  ABA  No.  121000358,  at  such  account  number)"  in lieu of the
existing  phrase  "maintained by the Borrower with Wells Fargo Bank, N.A. at its
office  at 121 Park  Center  Plaza,  San Jose,  California  95172,  Account  No.
684501705".

                  3. Condition of Effectiveness.  The effectiveness of Section 2
of this  Amendment  shall be subject to the condition that the Lender shall have
received on or before the date hereof this Amendment executed and delivered by a
duly authorized officer of the Borrower.

                  4.     Miscellaneous.

                           (a)  Agreement  Otherwise  Not  Affected.  Except  as
expressly  amended pursuant hereto,  the Agreement shall remain unchanged and in
full force and effect and is hereby ratified and confirmed in all respects.

                           (b)  Counterparts.  This Amendment may be executed by
one or  more  of the  parties  to  this  Amendment  in any  number  of  separate
counterparts,  each of which, when so executed, shall be deemed an original, and
all of said  counterparts  taken  together shall be deemed to constitute but one
and the same instrument. A set of the copies of this Amendment signed by all the
parties shall be lodged with the Borrower and the Lender.

                           (c) Governing Law. THIS  AMENDMENT  SHALL BE GOVERNED
BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF CALIFORNIA.

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Amendment to be duly executed and delivered by their proper and duly  authorized
officers as of the day and year first above written.

                                     KOMAG, INCORPORATED

                                       1.

<PAGE>

                                    By:     /s/ William L. Potts, Jr.
                                       ----------------------------------------
                                    Title: SVP, CFO
                                          -------------------------------------

                                    The DAI-ICHI KANGYO BANK, LIMITED,
                                    acting through its San Francisco Agency

                                    By:     /s/
                                       ----------------------------------------
                                    Title: General Manager & Agent
                                          -------------------------------------