The present invention relates to an apparatus for displaying an X-ray irradiation range for a dental X-ray image photographing apparatus. The apparatus for displaying an X-ray irradiation range is intended for a dental X-ray image photographing apparatus including a rotating body which rotates around the teeth of the human body, and an X-ray generator and an X-ray detector mounted on the rotating body such that the X-ray generator and the X-ray detector face each other, wherein the apparatus for displaying an X-ray irradiation range comprises: a collimator mounted on the X-ray generator to determine an X-ray irradiation range for the teeth a light-irradiating unit which indicates the upper and lower boundaries of the X-rays irradiated through the collimator and a controller which roughly reconciles the upper and lower boundaries of X-rays irradiated through the collimator and the irradiation range of the light irradiated from the light-irradiating unit. The above-described apparatus for displaying an X-ray irradiation range for a dental X-ray image photographing apparatus can easily check, from the outside, the X-ray irradiation range for teeth by means of the irradiation of light, the irradiation range of which corresponds to the X-ray irradiation range, and can correct the X-ray irradiation range by adjusting the collimator, thereby enabling the accurate photographing of the desired part.La présente invention concerne un appareil daffichage dune gamme dexposition aux rayons X pour appareil de radiographie dentaire. Lappareil daffichage dune gamme dexposition aux rayons X est destiné à un appareil de radiographie dentaire comprenant un corps tournant qui tourne autour de la dent de lêtre humain, et un générateur de rayons X et un détecteur de rayons X montés sur le corps tournant de manière à ce que le générateur de rayons X et le détecteur de rayons X soient en regard lun de lautre, lappareil daffichage dune gamme dexposition aux rayons X comprenant : un collimate
