PURPOSE: To process a part position to be worked such as the bad part position of a work in an automobile body and the like appropriately and surely.

CONSTITUTION: A part position to be worked such as the badly painted part position of an automobile body 1 transported on a transport line 2 is marked in an inspection marking process L1. This mark is detected with the mark detecting cameras S1, S2, S3 in a mark detecting process L2. In a grinding process L3, grinding tools T1, T2, T3 are moved to processing positions corresponding to the detected point and coordinates with grinding robots R4, R5, R6, and the like based on the data of the number of detected point and coordinates of the detected mark, and the part position to be worked is processed with the grinding tools T1, T2, T3.