PURPOSE: To obtain painting with constant quality, by relatively moving the position of a coating apparatus with respect to a conveyor in synchronous relation to the variable speed control of the speed of the conveyor.

CONSTITUTION: A car body B is conveyed at a predetermined speed N by a continuous driving type conveyor 1 in a state mounted on a truck C. An automatic painting apparatuses 4, 5 are equipped with painting machines 7, 8 and moved on a guide rail 12 in parallel to the conveyor 1 by a motor 10. If the distance l1 between the automatic painting apparatuses 4, 5 and the distance l2 between the automatic painting apparatus 5 and a touch-up process are mutually equal, the time t1 required before a painting completed car body B by the painting apparatus 4 is fed in the next painting apparatus 5 is equal to the time t2 required before the car body B is fed in the touch-up process 6 from the painting apparatus 5. The variation of the set times t1, t2 corresponding to the speed V of the belt conveyor is prevented.