To facilitate a work performed between an automated guided vehicle and a mount for products and reduce the occupying space by providing double wheels, whose center distance is longer than the gap between a guide rail and a storage rail, in the letting-out end side of a carriage frame provided in a transfer mechanism.

In transferring a carriage frame, the center distance between wheels 2a, 2b in the front end side is longer than a gap G between a guide rail 1d and a rail 7a so that the succeeding wheel 2b becomes to be put on the guide rail 1d in a section where the foremost wheel 2a overpasses the gap G off the rear end of the guide rail 1d. The front end wheel 2a is thus transferred on the rail on a coil mount and the succeeding wheel 2b passes over the gap G so that the wheels 2a, 2c are put on the guide rail 1d and the rail 7a and the carriage frame can be transferred in the rail side irrelevant to the presence of the gap G.