To moderate shock and secure safety of an occupant by setting a hydraulic shock absorber so that a commanding signal from a controller can change a high or low level of generating/damping force and a signal from a car speed sensor attached to a car body can be inputted into a controller.

A hydraulic shock absorber 1 is set to allow high or low adjustment of generating/damping force with the rotation of a built-in control valve, and an actuator for rotating a control rod connected with this control valve is driven by a commanding signal from outside. In the hydraulic shock absorber 1 into which a signal from a car speed sensor S is inputted through a controller C, for example, even when a driver does not recognize collision hazard due to doze or looking-aside, generating/damping force is changed to high or low level to generate optimum absorbing energy according to car speed.