A blade drive device includes: a blade; a drive source that drives the blade; and a chassis that has an opening opened and closed by a driving of the blade, and that houses the blade and the drive source. The drive source includes: a rotor that is rotatably supported; and a stator around which a coil for excitation is wound and which applies a rotational force to the rotor. The stator is formed along an inner side surface of the chassis and has a rectangular shape.