A guide bar used in a video lens barrel in the related art has problems of deterioration in supporting accuracy of the lens retaining frame, high manufacturing cost, and upsizing of the lens barrel. Also, in a cam pin type lens barrel, how the lens retaining frame is supported by the cam pins may not be clear. Therefore, by providing a plurality of guiding members on the inner surface of the fixed barrel of the lens barrel, and allowing a plurality of engaging portions on the lens retaining frames to engage the guiding members, the lens retaining frames are supported so as to be capable of moving in the direction of the optical axis. By differentiating the length of engagement of the respective engaging portions, the roles of the respective engaging portions on the lens retaining frames for supporting the lens unit in a space are clarified.