PURPOSE: To effect the upward and downward movements and the bi-directional gripping or positioning movements of fingers while using only one cylinder device.

CONSTITUTION: A lifting drive piston 7 and a gripping piston 8 are mounted respectively in upper and lower positions inside a cylinder 12 and a spring 6 is interposed between the two pistons. A pair of fingers 13, 13' freely rotationally journaled to a gripper 12 coupled to the lower portion of the gripping piston are engaged with a locking protrusion 11 at the lower end of a driving rod 9 in a manner permitting the rotation of the fingers about pivots, the driving rod 9 being formed integrally with the lifting drive piston. Thereby the rising and falling movements of the fingers are effected by the integral movement of the two pistons and the opening and closing gripping movements of the fingers are effected by the relative movements of the two pistons.