A valve control device is configured to execute a specific valve control when a valve switching condition at high pressure is satisfied. The specific valve control switches the spring constant change valves for front wheel to a blocking state and switches a spring constant change valves for rear wheel to a communication permission state. The valve switching condition at high pressure is satisfied when oil pressure of hydraulic oil of rear wheel side oil hydraulic cylinders, which is detected by rear wheel side oil pressure detection means, is more than or equal to a predetermined oil pressure threshold and the traveling state determination means determines that a vehicle is in a predetermined traveling state.