PURPOSE: To chuck a work as well as to aim at the promotion of shortening working hours, by installing a slide plug whose tip part has an engagement groove engaging a coupling pin and the rear end part is fitted into a clamper hole with some play, while rotating the slide plug a turn or so.

CONSTITUTION: A body 11 of a chucking device has a chucking part 11a grasping a work, and a clamper 12 is rotatably pivoted to this body 11 by means of a hinge 13. The rear end of a slide plug 17 is fitted inside a hole 12b of the clamper 12 with some play and the tip part is slidably fitted into a fit hole 15b of a screw member 15. At the tip part of the slide plug 17, a hook-shaped engagement groove 18 to engage with a coupling pin 16 installed in the screw member 15 is formed up while at the other end, a head 19 for rotating the slide plug is installed. When this head 19 rotates, the member 15 moves forward as rotating together with a bush 14 in a screw motion, so that the work is chucked by pressure at checking parts 11a and 12a in conjunction with the body.