A secondary battery, a wireless charging circuit connected to the secondary battery, an outer casing member that has an outer shape equivalent to an outer shape of a universal battery and accommodates the secondary battery and the wireless changing circuit, and a positive terminal and a negative terminal that are electrically connected to the secondary battery and are provided at positions corresponding to positions of a positive terminal and a negative terminal, respectively, of the universal battery, are provided. The wireless charging circuit includes a power reception protecting circuit that stops power reception at a rectifier circuit in a case where a received voltage exceeds a predetermined voltage range.