To reduce to a minimum the number of wires of a wire harness connecting an operation box with a controller, while ensuring the amount of information (signals) inputted and outputted between the operation box and the controller in an electric motor coach.

In this electric motor coach, an operation box 2 equipped with switches and display parts and a controller 14 for electrical control are so arranged at mutually isolated positions that the electrical signals can be mutually transmitted via a plurality of wires. In this case, an I/O integrating circuit is installed, and one from among the wires connecting the operation box with the controller 14 is connected with the I/O integrating circuit. As a result, both an input signal (ON/OFF of an 'economizing' SW) from the operation box 2 to the controller 14 and an output signal (lighting of LED) from the controller 14 to the operation box 2 are transmitted through the one wire connected with the I/O integrating circuit.