A servo unit includes a main controller, inverter units configured to control different motors in accordance with a command from the main controller, and a power unit that is configured to supply direct current power to each of the inverter units and that is communicable with the inverter units in parallel. The inverter units include a single key inverter unit. The main controller and the power unit communicate with each other via the key inverter unit that is a relay. The power unit controls power supply based on a power source control command transmitted from the main controller.