PURPOSE: To provide quick and efficient grinding of either a hollow part solely or the inner surface of hollow part together with the external surface by embedding each work with hollow part in free grinding substance using a jig, inserting a rotary resist member in the hollow, and by stirring the free grinding substance through rotation of said resist member.

CONSTITUTION: After locational adjustment of a rotary resist member 5 and a work to be processed 10 with hollow part mounted on a jig 4, a grinding through 1 containing free grinding substance is raised so that the work 10 is buried in the grinding substance, wherein the said rotary resist member 5 is inserted in the hollow, followed by rotation of the resist member 5 using a drive motor 7. After a specified period of time with grinding, the motor 7 is stopped and the grinding trough 1 is sunk, and rinse is made with water from a shower 8 followed by rise of said rotary resist member 5, and when the work 10 is unloaded. According to this arrangement in which free grinding substance put in a hollow is stirred and run against the inner surface of the hollow to accomplish barrel grinding, either the hollow solely or the inner surface of the hollow to accomplish barrel grinding, either the hollow solely or the inner surface of the hollow together with the exterior surface can be ground efficiently in a short time.