PURPOSE: To facilitate introducing of vacuum conditions and enable high speed rotation in a vacuum chuck in a robot handling by providing a hole for introducing the vacuum conditions inside a coupling interposed between a driving shaft and a non-driving shaft.

CONSTITUTION: A coupling 3 is interposed between a drive shaft 1 and a non- drive shaft 2 and connected with rings 4A, 4B and sealed with an O-ring 5A. Inside the drive shaft 1, coupling 3 and the non-drive shaft, a hole for introducing relating vacuum conditions is provided. The conditions is sealed with the O-ring 5A and O-rings 5B, 5C between the coupling 3 and a cylinder 6 to facilitate the vacuum introduction. Since there is no wear in the O-rings 5A-5C, high speed rotation is facilitated.