With an electric compressor including a rotational shaft, a compressor wheel disposed on the rotational shaft, and an electric motor for applying a rotational force to the rotational shaft including a rotor fixed to the rotational shaft, and a stator disposed around the rotor, for applying the rotational force to the rotor by an electromagnetic force, a vibration/noise reduction device includes a detector for detecting a frequency related to a vibration of the stator, and a signal generator for generating a vibration signal that has a frequency of a predetermined integral multiple of an electrical angle frequency, which is obtained from the frequency detected by the detector, and has a signal wave attenuating the vibration of the stator, and a vibrator for vibrating the electric compressor based on the vibration signal.