To provide a pressurizing device which makes it possible to obtain great working power in a working unit while assuring a relatively large stroke.

A boosting section of the pressure attachment equipped with the boosting section driven by a driving means on a substrate comprises a working cylinder 22, a pump piston 28, a plunger 25 and working piston 26 interposed in the working cylinder and arranged to face each other and a pump piston 29 interposed in the pump cylinder. One end of the plunger and the rod of the pump piston are connected and the rod of the working piston is formed engageably with the body to be pressurized. The plunger and the pump piston are driven by movement of the driving means to the side of the body to be pressurize. The body to be pressurized is worked by the plunger, the liquid in the working cylinder and the working piston.