PURPOSE: To exactly execute aperture interlocking with a camera side irrespective of a shift state, by connecting an aperture ring and an aperture operating ring with an operating string, and tensing the operating string to constant length irrespective of the extent of shift of a lens.

CONSTITUTION: When a photographer turns an aperture operating ring of a lens, an aperture ring 5 turns and an aperture blade 6 is operated. In this case, the extent of turning of the aperture ring 5 is transferred to an operating string 7, and the aperture operating ring 3 is turned by the same extent as the extent of turning of the aperture ring 5. In this case, a position of a guide pin 9, a hook member 20, and a supporting shaft 34 of a lever 15 is not moved, and pulleys 16, 17 are positioned by a controlling string 18, therefore, a position of pulleys 10, 11 is not varied, the extent of turning of the aperture ring 5 is transferred exactly to the aperture operating ring 3, and accordingly, by an interlocking piece 21 of the aperture operating ring 3, a member related to the aperture of a comera side is operated in accordance with the extent of the aperture ring 5.