PURPOSE: A method for acquiring a tomography image is provided to acquire an X-ray image of a subject regardless of the size of an X-ray sensor. CONSTITUTION: A method for acquiring a tomography image includes a first step and a second step. The first step is performed to locate a subject between an X-ray light source and an X-ray sensor(200). The second step is performed to acquire an X-ray image using the X-ray light source and the X-ray sensor. The X-ray image is acquired by rotating a photographing focus of the X-ray sensor and the X-ray light source at the same time along the same direction for the subject. The rotation center of the X-ray sensor and the X-ray light source is located at the photographing focus and moves from one end to the other end of the subject.
