A motor device includes a motor, an input unit, a processing unit, and an electrical energy storage unit. The input unit accepts power supplied from a controller during a first period and receives at least a communication signal transmitted from the controller during a second period after the first period. The processing unit updates data for the motor in accordance with the communication signal received by the input unit. The electrical energy storage unit stores, based on the power supplied to the input unit, electrical energy for driving the processing unit.