PURPOSE: To prevent the lowering of vehicle height during the travel on a bad road by performing normal control when the main pressure of a hydraulic circuit during the travel on the bad road is the specified value, and subtracting the compensation value from the target flow quantity to obtain the target value when the main pressure is lowered, thus controlling the discharge of a flow control valve.

CONSTITUTION: Upon the input of detection signals from a delivery pressure gauge 12, a liquid pressure sensor 13, a vehicle height displacement sensor 14, a vertical acceleration sensors 15a-15c, a lateral acceleration sensor 16, a steering angle sensor 18 and a vehicle speed sensor 19, a control unit 17S computes on the basis of these detection signals and controls a proportional flow control valve 9 to control a suspension characteristic variably. When the main oil pressure P detected by the sensor 12 is the specified value PO or higher, normal control is performed, and when the main pressure is lowered (P<PO) during the travel on a bad road, the compensation value is read, and the compensation value QC is subtracted from the computed target flow quantity QT. This subtraction is performed only at the discharge time so as to suppress the discharge quantity.