To ease a problem such as a low frequency response and a low reliability generated when a contaminated operation oil whose viscosity is changed in a low hydraulic pressure system is used.

This hydraulic device 10 has a single stage of electrohydraulic clevis type pressure control valve 40, which outputs a compensation signal of the control pressure corresponding to the control pressure in a control pressure chamber 60, and has a control piston 106 to convert the pressure control valve 40 from an integral controller to a proportional controller, and thereby, the stability of the control system is improved. The compensation to the variation of the viscosity generated resulting from the temperature variation of the operation oil can be realized by manufacturing the forked part 98 of the pressure control valve 40 and/or a regulation bridge part 62 with materials of different thermal expansion coefficients.