[Problem] To suppress current flowing to a contact of a relay when grounding a device to be grounded by connecting the contact of the relay, and to suppress arc discharge between relay contacts when the grounding state of the device to be grounded is released by disconnecting the relay contact.[Solution] A grounding circuit equipped with: a first relay contact connected to a device to be grounded; a resistor that is connected between the first relay contact and an earth, and that suppresses current flowing to the first relay contact when the contact of the first relay is closed; and a second relay contact that is connected in parallel with the resistor, and that is closed before the first relay contact is opened when the grounding state of the device to be grounded is released.