A barrel assembly of a zoom camera includes a front lens frame where a front lens group is installed, a front guide frame for supporting the front lens frame, a zoom ring advancing and retreating along an optical axis of the front lens group, an inner helicoid ring installed to be capable of advancing and retreating with respect to the zoom ring, a rear lens frame where a rear lens group which is arranged on the same optical axis as the front lens group is installed, and a cam unit formed at the zoom ring and an inner rotator which is installed at the inner helicoid ring to be capable of advancing and retreating, for adjusting the interval between the front lens group and the rear lens group as the front lens group moves.