A laser beam phase-modulation device, a laser beam steering device, and a laser beam steering system including the same are provided. The laser beam phase-modulation device includes a refractive index conversion layer having a refractive index that is changed according to an electrical signal applied thereto, the refractive index conversion layer including an upper surface on which the laser beam is incident and a lower surface opposite the upper surface, at least one antenna pattern embedded in the upper surface of the refractive index conversion layer, and a metal mirror layer provided under the lower surface of the refractive index conversion layer and configured to reflect the laser beam.