To greatly reduce energy consumption without providing an auxiliary hydraulic source.

This device includes a hydraulic pump 3 driven by a motor 2, a direction control valve 4, a hydraulic cylinder 5, a hydraulic piping 6 supplying hydraulic fluid to operate the hydraulic cylinder 5 in a designated direction or hold the hydraulic cylinder 5 in corresponding to a condition of the direction control valve 4, a pressure control valve 7 controlling pressure by returning at least part of hydraulic fluid discharged from the hydraulic pump 3 to a fluid tank 1, a pilot check valve 8 provided in a hydraulic circuit requiring pressure retaining and preventing reverse flow of hydraulic fluid, a pressure detection part 9 attached to the hydraulic piping located between the hydraulic cylinder 5 and the pilot check valve 8 and detecting pressure, and a controller 10 controlling the motor 2 with inputting pressure detected with the pressure detection part 9.