Disclosed is an X-ray image forming device is disclosed. The device includes an X-ray imaging unit including a rotating member rotatable about a rotating shaft and linearly movable, and an X-ray source and an X-ray sensor disposed at opposite ends of the rotating member to face each other with a region of interest therebetween, a penetration data acquisition unit configured to acquire X-ray penetration data from multiple directions crossing through an image layer in the region of interest by controlling the X-ray imaging unit and an image reconstructor configured to generate projection data in a predetermined angle range at each section of the image layer from the X-ray penetration data, and reconstruct a two-dimensional X-ray panoramic image of the image layer based on the projection data.