A magnet chuck includes a piston that is displaced inside a second sliding hole of a cylinder tube. One end surface of the piston abuts against a plate member when the piston reaches one displacement end point, whereas another end surface of the piston abuts against an entry member of a head cover when the piston reaches another displacement end point. At least one, and preferably both, of a first damper on the one end surface, and the second damper on the other end surface are disposed on the plate member.