To provide a chuck device in which holding power of a workpiece at a chuck part can be changed and the chuck part can be easily replaced.

A chuck device comprises a chuck part 50 having a holding part 10 which can be freely opened/closed, and a first supply system 31 for supplying air A to the holding part 10. A cylinder chamber 31t is provided in the first supply system 31, a movable pressure piston 31j is provided in the cylinder chamber 31t, and a check valve 31s which can be freely opened/closed is provided to the pressure piston 31i. The check valve 31s is so arranged that the check valve 31s is opened when the air A is supplied to a first passage 31b of the first supply system 31 and is closed when the pressure piston 31j is moved. When the pressure piston 31j is moved in a state that the holding part 10 is closed, the first passage 31b of the first supply system 31 is closed, and application force for closing the holding part 10 is adjusted by movement of the pressure piston 31j.