LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS

The undersigned, as a Section 16 reporting person of Arcus Biosciences, Inc., a
Delaware corporation (the "Company"), hereby constitutes and appoints each of
Terry Rosen, Ph.D., Juan C. Jaen, Ph.D., Carolyn Tang, Jason Barker, Jennifer
Yip, Kenneth Guernsey, Brett White and Eric Steiner signing individually, the
undersigned's true and lawful attorney-in-fact to:

(1)	complete and execute Form ID, "Update Passphrase Confirmation" form and
Forms 3, 4 and 5 and other forms and all amendments thereto as such
attorney-in-fact shall in his or her discretion determined 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 grants to the attorneys-in-fact full power and authority
to do and perform any and every act and thing whatsoever requisite, necessary or
proper to be done in the exercise of any of the rights and powers herein granted
and hereby ratifies and confirms all that said attorneys-in-fact and agents
shall do or cause to be done by virtue of this Power of Attorney.  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 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
foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 23rd day of November, 2020.

By: /s/ Andrew Perlman
Name: Andrew Perlman