A hydraulic suspension system includes a suspension base (16) supporting wheels, a hydraulic cylinder (19) for displaceably suspending the suspension base from a vehicle body, and an oil passage connected to the hydraulic cylinder. An accumulator (21, 23) is incorporated within the oil passage. A flow control valve (51) is incorporated at an oil passage portion between the hydraulic cylinder and said accumulator for controlling an amount of work oil flowing therebetween. A pressure sensor (56) is provided for detecting a cylinder oil passage pressure effective on the hydraulic cylinder. A control unit (57) is provided for controlling operation of the flow control valve, based upon a detection value from the pressure sensor.