A system to align an object using a light reflector, including: an input unit for pre-setting a first region in which radiation is to be emitted to the object; a display unit for displaying information on the first region; a radiation unit for emitting radiation to the first region; a reflector formed to correspond to the shape of the first region and configured to be attached to the first region; a light unit for emitting light in the same direction as the radiation to the first region; a camera for photographing a region of the reflector when the reflector reflects light emitted by the light unit; and a control unit for controlling the display unit to display the region of the light reflector which reflects light photographed by the camera, and determining whether the radiation is aligned to the first region of the object based on whether the region of the light reflector is included in the shape of the first region.