To provide a lens barrel that is excellent in heat conduction characteristic between the internal part and external part of the lens barrel, with a lens group between them, and that is almost free from deformation and bend in a lens composing a lens group.

A lens barrel 1 comprises a first group frame 5 which is a lens frame holding a first lens 21 and the second lens 22. The first lens 21, second lens 22, and first group frame 5 are configured so as to separate the internal space of the lens barrel 1 from outside space. The first lens 21 and/or second lens 22 has a recessed and projecting portion 31, formed outside the optical effective diameter of the lens face that is not opposite the other lens.