An on-board fluid machine includes a housing configured to allow fluid to flow into the housing, an electric motor accommodated in the housing, and a driver that is supplied with DC power and drives the electric motor. The driver includes a low-pass filter circuit and an inverter circuit. The low-pass filter circuit includes a common mode choke coil and a capacitor. The driver further includes a damping unit located at a position where magnetic field lines produced by the common mode choke coil generate eddy current.