An X-ray imaging apparatus for providing an X-ray CT image, a threedimensional image and also an X-ray panoramic image for image layers distributed along an arch trajectory, the apparatus comprising: a rotation supporter rotating based on a rotation shaft; a generating unit disposed in a first side of the rotation supporter and including an X-ray generator radiating an X-ray beam; a sensing unit disposed in a second side of the rotation supporter to face to the generating unit with a subject in between, and including a small width sensor (311E, 311F, 311G) moving in a width direction thereof and perpendicular to the rotation shaft when the rotation supporter rotates; and a controller changing a rotation speed of the rotation supporter or a frame rate of the sensing unit when performing an X-ray imaging sequence obtaining a number of transmitted images by rotating the rotation supporter, wherein the X-ray imaging apparatus is adapted to obtain the number of transmitted images and to obtain and store geometry information of an angle of rotation of the rotation supporter and position information of the small width sensor (311E, 311F, 311G), and is adapted to obtain a magnification ratio value for each transmitted image by using the geometry information and coordinate information of the arch trajectory, wherein the controller compensates a change in magnification ratio by changing the rotation speed of the rotation supporter or the frame rate of the sensing unit according to a change in distance between an area of interest of the subject and the small width sensor (311E, 311F, 311G) that is due to an arrow or arc form rather than circular form of the arch trajectory, wherein the magnification ratio is the ratio of a distance between a focal point of an X-ray beam and the small width sensor (311E, 311F, 311G) divided by a distance between the focal point of the X-ray beam and the subject. a rotation supporter rotating based on a rotation shaft; a generating unit disposed in a first side of the rotation supporter and including an X-ray generator radiating an X-ray beam; a sensing unit disposed in a second side of the rotation supporter to face to the generating unit with a subject in between, and including a small width sensor (311E, 311F, 311G) moving in a width direction thereof and perpendicular to the rotation shaft when the rotation supporter rotates; and a controller changing a rotation speed of the rotation supporter or a frame rate of the sensing unit when performing an X-ray imaging sequence obtaining a number of transmitted images by rotating the rotation supporter, wherein the X-ray imaging apparatus is adapted to obtain the number of transmitted images and to obtain and store geometry information of an angle of rotation of the rotation supporter and position information of the small width sensor (311E, 311F, 311G), and is adapted to obtain a magnification ratio value for each transmitted image by using the geometry information and coordinate information of the arch trajectory, wherein the controller compensates a change in magnification ratio by changing the rotation speed of the rotation supporter or the frame rate of the sensing unit according to a change in distance between an area of interest of the subject and the small width sensor (311E, 311F, 311G) that is due to an arrow or arc form rather than circular form of the arch trajectory, wherein the magnification ratio is the ratio of a distance between a focal point of an X-ray beam and the small width sensor (311E, 311F, 311G) divided by a distance between the focal point of the X-ray beam and the subject.