POWER OF ATTORNEY

The undersigned, as a Section 16 reporting person of Komag Incorporated (the
"Company"), hereby constitutes and appoints Jan Schwartz and Kathleen A.
Bayless, and each of them, the undersigned's true and lawful attorney-in-fact
to:

1.	complete and execute Forms 3, 4 and 5 and other forms and all amendments
thereto as such attorney-in-fact shall in his or her discretion determine to be
required or advisable pursuant to Section 16 of the Securities Exchange Act of
1934 (as amended) and the rules and regulations promulgated thereunder, or any
successor laws and regulations, as a consequence of the undersigned's ownership,
acquisition or disposition of securities of the Company; and

2. do all acts necessary in order to file such forms with the Securities and
Exchange Commission, any securities exchange or national association, the
Company and such other person or agency as the attorney-in-fact shall deem
appropriate.

The undersigned hereby ratifies and confirms all that said attorneys-in-fact and
agents shall do or cause to be done by virtue hereof.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the Company
assuming, any of the undersigned's responsibilities to comply with Section 16 of
the Securities Exchange Act of 1934 (as amended).

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

	IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 3rd day of October, 2006.


Signature: 	/s/ Edward J. Casey
Print Name: 	Edward J. Casey