An interchangeable lens unit comprises a second lens group unit, a focus lens unit, a fourth lens group unit, a zoom ring unit, and a focus motor. The zoom ring unit mechanically transmits operational force inputted to a zoom ring to the second lens group unit and the fourth lens group unit. The focus motor electrically drives the focus lens unit in the Z axis direction with respect to the second lens group unit. When the zoom ring is operated in a state in which no power is being supplied to the focus motor, a gap is always ensured in the Z axis direction between the focus lens unit and the second lens group unit.