A blade driving apparatus for cameras includes a base plate having an aperture for a photographing optical path; a cover plate having the aperture for the photographing optical path, provided with a blade chamber between the base plate and the cover plate; at least one blade rotatably mounted to the base plate in the blade chamber; and at least one electromagnetic driving source driving the blade. The electromagnetic driving source includes a rotor magnetized to have a plurality of magnetic poles at preset angles on its peripheral surface and having a driving pin for driving pin for driving the blade by its rotation, a yoke having a plurality of magnetic pole sections opposite to the peripheral surface of the rotor, and a coil wound through the yoke. At least, the rotor and the yoke are interposed between the base plate and the cover plate so that, at least, the rotor is rotatably mounted to the base plate.