PURPOSE: To perform the shower test of the body of a vehicle under a state close to an actual running, by setting the desired place of a conveyor carrying the vehicle high or low as compared with a usual level.

CONSTITUTION: A large number of the water jet nozzles S of a shower tester are arranged above the endless flat conveyor 2 arranged to a shower test line. Conveyors 3, 4 have protruding parts protruding with respect to a usual level or cavities depressed with respect to said level formed thereto by guide rails 6, 7 consisting of upper side guide parts 6a, 7a and lower side guide parts 6b, 7b for guiding the upper sides 8a, 9a and lower sides 8b, 9b of free rollers 8, 9. Therefore, the feed surface of a vehicle formed by this conveyor apparatus 2 becomes an undulated surface to make it possible to certainly reproduce an actual test state and a shower test becomes possible in such a state that stress is applied to the body of the vehicle.