PURPOSE: To avoid any contact with burrs and the like to achieve chucking by forming the first claw parts which hold a positioned part and the second claw part which consists of a recess on the mutually opposing surfaces of a chucking claw opposite-arranged around an attracting means.

CONSTITUTION: The second claw parts 12b cut into approximately V shapes in the mutually opposing surfaces of a chucking claw 13 are formed, and at the top and the bottom of which the third claw parts 12c and the first claw parts 12a are formed to accommodate a positioned part 11 between the claw parts 12a, 12c and the part is held by the claw parts 12b. Even if burrs exist on the positioned part 11, inclined surfaces 15 come into contact with the lower edge of the positioned part 11, so that the positioned part 11 can be held and any contact with burrs 20 can be avoided by means of a recess, so as to achieve correct positioning. When the claw parts 12c hold the positioned part 11, it is thus possible to preven the positioned part 11 from protruding upward even if it slips on a contact surface between the positioned part 11 and the claw parts 12b.