To provide a clamp cylinder with use of a hollow ultrasonic motor, for use in place of a pneumatic clamp cylinder.

A hollow motor type clamp cylinder is provided with a cylinder body 2, the outer side surface of which is vertically installed with a body latching part 5 with a mounting hole 51 bored therethrough. Inside the cylinder body 2 is provide with a hollow ultrasonic motor 3 provided with a motor drive hole at the center, and fixed such that the center of the motor drive hole matches with the cylinder center of the cylinder body 2. The outside the motor drive hole of the hollow ultrasonic motor 3 is provided with a shaft guide 6 guiding a driving shaft 4, which is installed to pass through the shaft guide 6 and the motor drive hole. A one end of the driving shaft 4 positions outside the side surface which is adjacent to the side surface installed with the body latching part 5 of the cylinder body 2. The one end is provided with a jig latching part 7 with a mounting hole 71 bored therethrough. The hollow ultrasonic motor 3 is electrically connected with a driving unit 9 for driving thereof.