An image pickup apparatus is disclosed which prevents interference of a lens barrel with an optical member and so forth with certainty and is advantageous in achievement of reduction in scale, weight and cost of the optical member and an adapter ring. If it is detected by a detection section that an adapter ring is attached to an adapter ring attachment portion, then a lens barrel control section moves a lens barrel so that a front end of the lens barrel is positioned within a range rearwardly of a front end of the adapter ring. Since the front end of the lens barrel does not project forwardly of the front end of the adapter ring, the end of the lens barrel does not interfere with a conversion lens or the like attached to the front end of the adapter ring. It is not necessary to form the wide conversion lens or the adapter ring with an increased size in order to prevent the front end of the lens barrel positioned at its projecting position from interfering with a lens of the wide conversion lens.