To provide a pressure intensifying system efficiently utilizing liquid in the system and intensifying the pressure after using the liquid as hydraulic pressure of a hydraulic pressure supply source, and to provide a drive system using the same.

The pressure intensifying system A2 is a device for driving the drive device 3 by using the hydraulic pressure supplied from the hydraulic pressure supply source W. The pressure intensifying system A2 includes: a drive-side piston cylinder mechanism 1 driven by the hydraulic pressure supplied from the hydraulic pressure supply source W; a driven-side piston cylinder mechanism 2 reciprocated through hydraulic supply paths P3, P5 by reciprocating motions of a drive piston 12 of the drive-side piston cylinder mechanism 1; and a pressure intensifying device B1 disposed to the hydraulic supply paths P3, P5 and further intensifying the hydraulic pressure that has been intensified by the drive piston cylinder mechanism 1, and thereby to drive the driven-side piston cylinder mechanism 2. The pressure intensifying system A2 intensifies drive pressure loaded on the driven-side piston cylinder 2 with respect to original pressure of the hydraulic pressure supply source W.