To enable adjustment of a lens frame (lens barrel) independently, and also to enable a reduction in thickness along the optical axial direction. A blade driving device having a driving member for moving on a plane; a frame for containing the driving member; a thin blade supporting unit that protrudes to the outside, along the direction of movement of the driving member, from a portion of the thickness of the frame, and that has an opening, around the optical axis, along the direction of thickness of the frame; and a blade member that is supported on the blade supporting unit, and that is moved by the driving member, to advance into the opening; wherein the outer peripheral edge of the frame has a recessed portion at the position at which the blade supporting unit protrudes.