PURPOSE: To effect a processing work in a state that objects to be conveyed are sufficiently laterally spaced away from each other by a method wherein a pair of the support parts on both sides for an object to be conveyed of a trolley device runnable on a specified route are movable individually in a lateral direction.

CONSTITUTION: Guide rails 27 laterally protruded and inclined such that a level is gradually raised toward an outer end are interconnected on both sides of a coupling frame 26 mounted on a trolley device 6 movable in a state to be supported and guided by a rail 2 for guiding a trolley. A pair of support parts 7 on both sides individually movable in a lateral direction in a state to be supported and guided by the guide rails 27 are provided. The support part 7 comprises a pair of trolley members 31 on both sides, a flat frameform frame 32 located between the lower parts of the trolley members, and a hanger 31. The support part 7 is stopped in a given spot (a painting room and the like) 50, and transferred to a moving guide rail 59 through operation of a transfer device 62 in a state that the moving guide rail 59 is joined with the guide rail 27.