PURPOSE: To improve productivity by finding the order with the assembly main body flowing a painting line being input with its being leveled to an assembly line, based on an assembly specification information and registered leveling conditions, also indicating the production start time of an assembly part corresponding to the assembly main body.

CONSTITUTION: A vehicle recognizing part 21 as for an assembly main body clasification recognizing part, a vehicle specification information control part 41 as for an assembly specification information control part, and a leveling processing part 30 are equipped with. The leveling process part 30 finds the order that the vehicle main body flowing a painting line 2 is input with its being leveled to an assembly line 3, based on the information from the vehicle specification information control part 41, the identification signal from the vehicle recognizing part 21 and the leveling conditions registered via a data in and output part 51, also finding the production start time of the assembly part corresponding to the vehicle main body input to the assembly line 3, and indicating this. The vehicle main body and assembly part can thus be coalesced with good timing.