EXHIBIT 5.1.1


                     Wilson Sonsini Goodrich & Rosati P.C.
                               650 Page Mill Road
                              Palo Alto, CA 94304



January 14, 2004


Komag, Incorporated
1710 Automation Parkway
San Jose, California 95131

RE:  REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:


          We have examined the registration statement on Form S-3 filed by you
with the Securities and Exchange Commission (the "Commission") on November 3,
2003, as amended on December 9, 2003, December 23, 2003 and January 12, 2004
(such registration statement as so amended, and as may be further amended or
supplemented herein the "Registration Statement") in connection with the
registration under the Securities Act of 1933, of 5,750,000 shares of common
stock (including up to 750,000 shares subject to an over-allotment option to be
granted to the underwriters), par value $0.01 per share, to be sold by you and
certain stockholders listed in the Registration Statement. As your counsel, we
have examined the transactions taken and proposed to be taken in connection with
the sale of such shares by you and such stockholders in the manner set forth in
the Registration Statement.


         It is our opinion that such shares, if sold by you and such
stockholders in the manner set forth in the Registration Statement, will be
legally and validly issued, fully paid and nonassessable.


         We are opining herein as to the effect on the subject transactions only
of the federal laws of the United States and the General Corporation Law of the
State of Delaware, and we express no opinion with respect to the applicability
thereto, or the effect thereon, of the laws of any other jurisdiction or, in the
case of Delaware, any other laws or as to any matters of municipal law or the
laws of any other local agencies within the state.


         We consent to the use of this opinion as an exhibit to the Registration
Statement, and further consent to the use of our name wherever appearing in the
Registration Statement, including the Prospectus constituting a part thereof,
and any amendment thereto.

                                            Sincerely,

                                            WILSON SONSINI GOODRICH & ROSATI
                                            Professional Corporation

                                            /s/ Wilson Sonsini Goodrich & Rosati