A device connected to a bus and a device driver for controlling the device, capable of preventing the device from falling into a forced use suspension (disable) state. Prior to notice of power consumption by a USB device connected to the bus(USB), the device driver acquires knowledge of remaining electric power that can be supplied by the bus. According to whether the remaining electric power is satisfactory for power consumption expected to be notified of by the USB device, the device driver permits the notice of power consumption by the USB device and causes the bus to start electric power supply, or executes avoidance processing in order to avoid shortage of power.