Miniaturization by simplification of a structure is achieved while suppressing a bound of an opening/closing blade and securing improvement of functionality. A blade opening/closing apparatus includes: a base body that includes an aperture; a driving body that is movably supported by the base body and is operated by a driving force of a drive source; an opening/closing blade that is moved by an operation of the driving body and opens/closes the aperture; and a braking body that controls a movement speed of the opening/closing blade via the driving body, the driving body including, on one surface thereof, an engagement portion that is to be engaged with the opening/closing blade and transmits the driving force to the opening/closing blade, the driving body including, on another surface thereof, a braked portion to which a braking force of the braking body is to be applied.