Disclosed are an X-ray irradiating device that has a function of selecting an automatic photographing mode and an X - ray imaging method using the same. The X-ray irradiating device, according to the present invention, comprises: an X-ray irradiation source a motion sensor that detects the direction in which the X-ray irradiation source is directed and a controller that selects one of multiple photographing modes according to the direction angle signal received from the motion sensor. The X-ray imaging method, according to the present invention, which uses the above-described X-ray irradiating device, comprises: a step for setting a reference plane that is the basis for the direction angle at which the X-ray irradiation source is directed a step for detecting the direction angle with respect to the reference plane using the motion sensor and selecting a photographing mode that corresponds to the direction angle and a step for performing X-ray imaging b y controlling the X-ray irradiation source with a set value corresponding to the selected photographing mode.
