One aspect of the present invention pertains to a railroad car having a plurality of electrical circuits. The railroad car is provided with: an external power source connection unit; a normally-closed contactor that opens or closes a common line for connecting the plurality of electrical circuits to the ground side, and that opens the common line in response to the supply of power from the external power source connection unit but closes the common line in the absence of power supply; and an operation prohibition determination unit that determines whether the supply of power to the plurality of electrical circuits has been stopped, and prohibits opening of the common line by the contactor when the power supply has not been stopped.
