LENS BARREL

PROBLEM TO BE SOLVED: To provide a lens barrel which can be miniaturized further.SOLUTION: A lens barrel includes a zoom optical system and a light quantity adjustment mechanism. The zoom optical system includes, in order from the subject side, a first lens group, a second lens group, and a third lens group. The second lens group move in a direction orthogonal to the optical axis of the first lens group to allow movement of the optical image. The lens barrel takes a photographable state and a collapsed state. In the photographable state, the first lens group, the second lens group, and the third lens group are arranged in the direction of the optical axis. In this state, at zooming operation, the first lens group and the third lens group move independent of each other in the direction of the optical axis. In this state also, at zooming operation, the light quantity adjustment mechanism and the second lens group integrally move along the optical axis. In the collapsed state, when viewed from the direction of the optical axis, the third lens group retreats in the direction orthogonal to the optical axis of the first lens group.