PURPOSE: To facilitate chuck changing-over and assemble various parts effectively by disposing respective pallet carrying devices in parallel, on which assembly parts and products are placed within the movable area of multiple assembling robots.

CONSTITUTION: Loaded parts of a stopped part pallet 10 are assembled by a stopper 20 in a product pallet 4 stopped by a stopper 21 by a robot 2. At this time, a robot 1 performs a change to a chuck for a part placed on a part pallet 11 by a chuck stock device 8. After assembly is completed by the robot 2, the stopper 21 releases stopping and the pallet 4 moves to a stopper 19. At the same time, the stopper 21 also releases stopping and a pallet stopper 16 releases stopping, so that the pallet 11 becomes ready to move. Because a carrying device 15 carries a pallet twice as high a speed as the carrying device 14, a pallet 10 moves out of the movable range of the robot 1, and while the pallet 4 moves to the stopper 19, the pallet 11 moves to the position of the stopper 18 and is stopped by a stopper 18.