A motor-driven compressor includes a compression mechanism for compressing a refrigerant gas, an electric motor, an inverter assembly and an inverter chamber. The electric motor drives the compression mechanism. The inverter assembly converts direct-current power into polyphase alternating-current power to supply to the electric motor and controls a rotational speed of the electric motor. A substrate having an electric circuit and an electronic component connected to the substrate are provided in the inverter assembly. The inverter chamber detachably accommodates the inverter assembly. A vibration damping member is arranged in the inverter assembly.