A lens barrel capable of distributing, upon receipt of the impact of, e.g., dropping, a torque load so as not to concentrate on a particular linear movement key and groove for linearly moving a barrel member, thereby suppressing occurrence of a failure. The lens barrel has a fixed barrel (8) and a third lens group barrel (3). In a movement region of the third lens group barrel (3) moving in the optical direction relative to the fixed barrel (8), each of a set of a first linear movement groove (8c) and a first linear movement key (3c) and a set of a second linear movement groove (8d) and a second linear movement key (3d) has a mutually engageable region and a mutually disengageable region, and a set of a groove (8e) and a projection (3e) has not a mutually engageable region.