A device for controlling a door operated by a motor includes an opening/closing mechanism that opens and closes the door, and a gear mechanism that includes a plurality of tooth units each of which has different mesh and that conveys a torque of the motor to the opening/closing mechanism. The tooth units include a low-torque tooth unit that convey a relatively low torque, and a high-torque-tooth unit that conveys a relatively high torque. The torque conveyed to the opening/closing mechanism is changed by selecting a tooth unit based on a position of the door at the time of starting an opening or closing operation of the door.