A printer has a controller configured to give an instruction to a LAN controller, the instruction specifying which one of communication speeds the LAN controller should communicate at. When it is determined that the mode of the printer is changed from a power mode in which power is supplied to the controller to a power mode in which power is not supplied to the controller, the controller instructs the LAN controller to reduce the communication speed. After the instruction to reduce the communication speed is given, a power supply unit cuts off power supply to the controller.