A camera having a zoom lens barrel that includes an aperture size changing mechanism including a pair of light intercepting members which are inserted into a retracted from a rectangular-shaped photographing aperture of the camera for changing the photographing aperture size. The camera further includes a non-rotational cylinder which moves in the direction of the optical axis of the zoom lens without rotating. A rotational cylinder is also included and is driven to rotate with respect to the non-rotational cylinder about the optical axis. A gear supporting member is supported on the non-rotational cylinder. The gear supporting member includes a raised portion projecting toward the photographing aperture. The camera further includes a gear train which is supported on the gear supporting member for transmitting a drive force to the rotational cylinder. At least a part of the gear train is supported by the raised portion, which is formed such that the orthographic projection thereof may not overlap the pair of light intercepting members in the optical axis direction.