Plural wok pairs composed of a plurality of works are stored in work storing means. A movable sensor 45 fitted to a conveyance robot 5 detects the position of one of the work pairs in the work storing means, and the work gripping means 25 takes out a plurality of works at one time from the work storing means. One of the plurality of works is held temporally by temporal work holding means 6 or 7 while the other work is conveyed to a jig Y. In the course of conveyance, a fixed sensor 63 detects the relative positional relationship between the work and the work gripping means 25. If the relative positional relationship deviates from the regular positional relationship, the movement of a robot arm 31 is corrected.