To necessarily and sufficiently restrain the play of a movable lens group by a compact and simple energizing mechanism, to prevent out-of-focus caused by the attitude difference of a camera and to avoid the lowering of the resolution of a photographed image.

The lens barrel is equipped with a lens barrel main body 10, a plurality of lens groups 11a to 14a housed in the main body 10 and including movable lens groups 12a, 13a and 14a moving in an optical axis OA direction, and the energizing mechanism 20 (30 and 40) giving energizing force in a direction parallel with the optical axis OA at least to one lens group 12a out of the lens groups 12a, 13a and 14a in the lens groups 11a to 14a when the lens group 12a is within a specified moving range X1 to X2.