A steer-by-wire steering device is provided with: a first stopper shaped hollow; a second stopper shaped hollow and structured such that a steering shaft is coupled to the second stopper, the second stopper including a small diameter portion and a large diameter portion; a nut engaged to a thread formed on an outer circumference surface of the small diameter portion such that the nut is positioned between the first stopper and the large diameter portion of the second stopper; and a hollow guide ring having an outer circumferential surface and an inner circumferential surface, the hollow guide ring provided between a housing and the nut such that the outer circumferential surface is coupled to the housing and the nut is coupled to be supported in the inner circumferential surface in a circumferential direction.