1. An X-ray imaging apparatus comprising: an X-ray generator which generates an X-ray and irradiates the X-ray onto a subject; a detector which detects the X-ray transmitted through the subject; and a device which obtains an image from the X-ray detected by the detector, obtains bone image information and soft tissue image information of the subject, based on the obtained X-ray image, and produces one image including the bone image information and the soft tissue image information.