To provide a working body for working on an object to hold or detect the object which is excellent in versatility.

A holder 3 as the working body has a part 3a to be fixed which is fixed to a third shaft part 7b on the side of the base end and a sucking disk 14 for holding a work 2 on the side of the tip. An air conduit of a vacuum device communicates with the sucking disk 14. The holder 3 has a ball joint 15 which can be locked by adjusting the rotation and consists of a ball part 15a and a socket part 15b in the intermediate part. As for the ball joint 15, the ball part 15a is arranged on the side of the sucking disk 14 and the socket part 15b is arranged on the side of the part 3a to be fixed. In the ball part 15a, an air-conduit hole 15c and an attaching/ fixing part 15d to which the sucking part 14 is fixed are provided. The air conduit communicates with the sucking disk 14 through the attaching/fixing part 15d from the hole 15c for the air conduit.