A camera with a lens barrel is provided which includes a first frame member having on an inner surface thereof a female helicoid, and a cam groove which has substantially a same lead angle as a lead angle of the female helicoid and which is deeper than the female helicoid. A second frame member is placed inside the first frame member. The second frame member includes a male helicoid engaged with the female helicoid, and a cam follower engaged with the cam groove. The first frame member is rotatable relative to the second frame member, so as to cause forward or backward movement of the second frame member.