A battery voltage detecting circuit includes: a first capacitor having one end connected to one input terminal of an operational amplifier; a second capacitor having one end connected to an output terminal of the operational amplifier and the other end connected to the one input terminal of the operational amplifier; a third capacitor having one end connected to the other input terminal of the operational amplifier; a fourth capacitor having one end applied with a reference voltage and the other end connected to the other input terminal of the operational amplifier; and a switching circuit configured to electrically connect the one input terminal of the operational amplifier to the one end of the first capacitor after the transient current has stopped flowing.