FIRST AMENDMENT AGREEMENT


                  This FIRST AMENDMENT AGREEMENT,  dated as of November 19, 1996
(this  "Agreement"),  is between  KOMAG,  INCORPORATED,  a Delaware  corporation
("Borrower"),  and THE INDUSTRIAL BANK OF JAPAN,  LIMITED,  SAN FRANCISCO AGENCY
("Bank"),  with respect to the Credit Agreement,  dated as of December 15, 1995,
between Borrower and Bank (the "Credit Agreement").

         The parties hereto agree as follows:

         Section 1. Definitions.  Terms defined in the Credit Agreement are used
herein with the same meanings unless otherwise specifically defined herein.

         Section 2. Amendments to the Credit Agreement.  The Credit Agreement is
hereby amended:

                   (a) To  amend  and  restate  in its  entirety  the  following
definition in Section 1.1 thereof as follows:

                           "Maturity  Date":   December  15,  2000,   unless  an
                  extension  shall  occur  under  Section  2.1,  in  which  case
                  "Maturity Date" shall mean the amended Maturity Date resulting
                  from such extension.

                  (b) To amend and  restate in its  entirety  subsection  (c) of
Section 2.3 thereof as follows:

                           (c) Eurodollar Rate Loans.  Revolving Loans which are
                  Eurodollar  Rate Loans shall bear  interest for each  Interest
                  Period with  respect  thereto on the unpaid  principal  amount
                  thereof  at a rate  per  annum  equal to the  Eurodollar  Rate
                  determined  for such  Interest  Period  plus 0.550  percentage
                  points.

         Section  3.  Effect.  Except as  specifically  set forth  herein,  this
Agreement does not limit,  modify,  amend, waive, grant any consent with respect
to, or  otherwise  affect (a) any  right,  power or remedy of the Bank under the
Credit  Agreement or any other Loan  Document,  (b) any  provision of the Credit
Agreement or any other Loan  Documents,  all of which shall remain in full force
and  effect and are hereby  ratified  and  confirmed.  This  Agreement  does not
entitle,   or  imply  any  consent  or  agreement  to,  any  further  or  future
modification  of,  amendment  to,  waiver  of, or  consent  with  respect to any
provision of the Credit Agreement or any other Loan Document.
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         Section 4.  Conditions of  Effectiveness.  This Agreement  shall become
effective  as of the date hereof  when Bank has  received a  counterpart  hereof
signed by Borrower.

         Section 5. Counterparts:  Facsimile  Signatures.  This Agreement may be
executed  in any  number of  counterparts  and by  different  parties  hereto in
separate  counterparts,  each of which when so executed and  delivered  shall be
deemed to be an original with the same effect as if all the  signatures  were on
the same instrument.  Delivery of an executed  counterpart of the signature page
to this  Agreement  by  telecopier  shall be effective as delivery of a manually
executed  counterpart  of this  Agreement.  Any  party  delivering  an  executed
counterpart  of the  signature  page  to  this  Agreement  by  telecopier  shall
thereafter  promptly deliver a manually executed  counterpart of this Agreement,
but the failure to deliver such manually  executed  counterpart shall not affect
the validity, enforceability, and binding effect of this Agreement.

         Section 6. Governing Law and Submission to Jurisdiction. THIS AGREEMENT
SHALL BE GOVERNED BY AND CONSTRUED IN  ACCORDANCE  WITH THE INTERNAL LAWS OF THE
STATE OF  CALIFORNIA  AND IS SUBJECT  TO THE  PROVISIONS  OF SECTION  8.8 OF THE
CREDIT  AGREEMENT,  RELATING TO SUBMISSION TO  JURISDICTION,  THE  PROVISIONS OF
WHICH ARE BY THIS REFERENCE HEREBY INCORPORATED HEREIN IN FULL.

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Agreement to be executed by their  respective  authorized  signatories as of the
date first above written.

                                   "BORROWER"

                                   KOMAG, INCORPORATED


                                   By       /s/ Stephen C. Johnson
                                      -------------------------------
                                   Title:   President & CEO
                                          ---------------------------

                                   "BANK"

                                   THE INDUSTRIAL BANK OF JAPAN, 
                                   LIMITED, SAN FRANCISCO AGENCY


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

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