To prevent the life from being shortened caused by the action of oil pressure having the specified value to a double acting hydraulic cylinder or a hydraulic pump by the delay of operation of a solenoid valve.

A hydraulic circuit for hydraulic pumps 3, 5 is for keeping oil pressure to be supplied to a double acting hydraulic cylinder 22 at the prescribed pressure or less. Even if a considerable time is taken until a solenoid valve 11 is switched from the Y position to the Z position after a micro switch 69 sends an ON signal, oil pressure in a first oil passage 28 communicated with a high-pressure line is discharged to an oil tank 7 through a high-pressure regulating device 41, and pressure in the first oil passage 28 can be immediately dropped. Accordingly, pressure in the first oil passage 28 does not exceed the prescribed pressure of 700kgf/cm2. When the double acting hydraulic cylinder 22 is used for a hydraulic tool such as a crimp tool or a compression tool, the lives of the double acting hydraulic cylinder 22 and the high-pressure hydraulic pump 5 can be remarkably lengthened.