This drive device, which controls an electric motor, is composed of a combination of a plurality of devices such as a circuit breaker, an electromagnetic switch, an inverter, and a servo amplifier. In the prior art, there has been a problem wherein the wiring for connecting devices of different types has been laborious because the position and specifications of a terminal differ depending on the device. Plugs with a unified specification are arranged on the side surfaces of devices of different types which are included in the drive device that controls the electric motor, and the plugs are installed so that the side surfaces of the devices are attached closely to each other through the connection of the plugs and the devices of different types are unified.