To provide a power storage device for regularly supplying power to a mobile electronic device, in which charging of a battery by a power feeder can be simplified and even when power stored in the battery is not enough, power can be regularly supplied to the mobile electronic device. The mobile electronic device includes an antenna circuit which receives power supply via radio signals, a battery which stores power, and a power supply control circuit which includes a switch circuit for intermittently supplying power to a load. Power supply to the load is intermittently controlled by controlling the switch circuit, which is provided in the power supply control circuit for controlling the supply of power stored in the battery, using a signal from a low-frequency-signal generating circuit.