PURPOSE: To cope with various work by means of one unit of unmanned truck.

CONSTITUTION: A lift motor for lifting a bed 3 is provided in an unmanned truck 1, and projections 5 are projectedly formed near the 4 corners on the bed 3. In the holes of the projections 5, a connector jointed to a power source through a cord for transferring power. In addition, an attachment area 9 is formed at a corner of a factory, at which an electromagnetic induction cable 2 branches into plural wires, and a plurality of stations 10 are provided so as to crossing over each head part. On the upper plate 12 of each station 10, various types of transfer equipment 15 through 17 having a recessed part opposing to the projection 5 on the bottom face and a hopper 18 (attachment) is placed so as to be held between a pair of positioning jigs 14. The bed 3 is lifted by a station 10 on which objective attachments 15 through 18 are placed to engage the projection 5 with the recessed part, mounting the attachments.