PURPOSE: To perform the exchange use of a hand, having a plurality of fluid passages, through simple and non-bulky piping structure.

CONSTITUTION: A fluid passage formed in a hand mounting part 10, to which various hands 1 are removable mounted and connected, and connected to the hand 1 side is incorporated in a hand mounting part 10 as a manifold 12 to branch a passage, running from one piping 21 on the working device 2 side, into the given number of branch passages. Branch passages 12a of the manifold 12 are opened to a surface 9 connected to the hand 1 of the hand mounting part 10 in a manner to be positioned facing respective openings 6, and valves 13 individually opened and closed are arranged in the respective branch passages 12a.