Vibration damping system and vehicle

It is possible to provide a vibration damping system and a vehicle that can accurately diagnose failure in a state that element components constituting the vibration damping system are remained to be installed without dismounting the element components and that can reduce energy consumption and shorten the time required for failure diagnosis. A control device of the vibration damping system comprises a voltage command producing part that produces the driving voltage command to drive an actuator and a vibration failure diagnosis part that diagnoses whether there is failure or not based on the vibration detection signal output by the vibration detecting device. In executing the normal mode in which the control to damp the vibration is conducted, the voltage command producing part produces the driving voltage command based on the vibration detection signal and makes the actuator generate the vibration applying force according to the driving voltage command. In executing the failure diagnosis mode in which the control to diagnose failure is conducted, the voltage command producing part produces the driving voltage command corresponding to the diagnosis frequency that is previously set at the frequency identical to the resonance frequency of the frame or the predetermined frequency close to the resonance frequency and makes the actuator generate the vibration applying force according to the driving voltage command, and the vibration failure diagnosis part diagnoses whether there is failure or not based on the vibration detection signal.