A truck apparatus for conveying parts includes supply rails laid to reach a delivering position for the parts, rails for a shift car laid perpendicularly to the supply rails, rails for two trucks to be coincided with the supply rails mounted at an interval on the shift car, and bearers for the parts each having a cradle roller placed on the rails for the truck. Each of the trucks includes lifters to vertically displace the bearers on the trucks. When one of the rails for the trucks on the shift car are disposed at a position to be coincided with the supply rails, the positions of right and left sides of the supply rails corresponding to the positions occupied by the other of the rails for the trucks are positions to be placed with the parts on the two bearers for the parts. Thus, the receiving and delivering preparation times of the parts and the transferring time of the truck between the rails can be shortened by simultaneously conducting the transferring work of the trucks between the supply rails and the rails on the shift car, thereby improving the working efficiency.