A lens barrel has a telescopic structure in which an inner barrel and an outer barrel move relative to each other. A plurality of ring retainers (201 and 202) are disposed at different positions with respect to the optical axis direction between an inner barrel (11) and an outer barrel (12) to support a number of bearing balls (30) so that the bearing balls (30) roll in contact with the inner barrel (11) and the outer barrel (12). The retainers (201 and 202) are supported floatingly in a direction parallel to the optical axis in accordance with the rolling movement of the bearing balls (30). The inner barrel (11) and the outer barrel (12), which move relative to each other, are supported by the ball bearings.