An object of the present invention to provide a semiconductor device including a battery that can be wirelessly charged, in which the battery can be charged even when the semiconductor device is not put close to a power feeder. Such a semiconductor device has a structure including an antenna circuit, a communication control circuit to conduct wireless communication via the antenna circuit, a battery to be charged with electric power which is externally wirelessly fed via the antenna circuit, and an oscillator circuit to wirelessly feed electric power via the antenna circuit. In addition, the battery in the semiconductor device is wirelessly charged and the semiconductor device externally feeds electric power wirelessly to a chargeable battery in another semiconductor device.