A switch circuit connects a switch (SW) to a connector when a connector receives a signal and connects the switch (SW) to a terminal when the connector receives power. The connector receives a signal and power transmitted at the same frequency, outputs the received signal to a communication unit through an attenuator, and outputs the received power to a power receiving unit. The communication unit carries out reception processing to the signal and outputs the processed signal to a computer. The power receiving unit carries out reception processing to the power and stores the processed power. The power receiving unit supplies the communication unit or the computer with the stored power.