Shock absorbers of left and right front wheel suspensions and shock absorbers of left and right rear wheel suspensions each are constituted by a damping force adjustable hydraulic shock absorber provided with a frequency response unit. An actuator of a damping force variable mechanism provided to the shock absorber is driven and controlled by a controller. The controller variably adjusts the damping force between the soft side and the hard side by the damping force variable mechanism according to a vertical vibration when a vehicle body vertically vibrates at a low frequency. The controller does not adjust the damping force when the vehicle body vibrates at a higher frequency than the low frequency.