An optical system apparatus having a lens barrel, including multiple lenses, that is shifted between a stored position in which the lenses are collapsed and a photographing position in which the lenses are aligned along an optical axis of the apparatus. A lens barrier covers at least a front side of a lens. A barrier driving unit moves the lens barrier between a closed position and an opened position for retracting the lens barrier out of an operation space of the lens barrel. A barrier control member prevents the lens barrier from moving to the closed position from the opened position when the lens barrel is in the photographing position.