In an X-ray imaging system, an X-ray source has a lightweight and small-sized X-ray tube. The X-ray tube is a fixed anode X-ray tube without having a target rotating mechanism. The X-ray tube uses a cold cathode electron source, which does not need a filament and a heater. An image acquisition control device moves the X-ray source to each of plural positions predetermined on a cross bar of a holder by control of a drive source of a shift mechanism. Whenever the X-ray source reaches each position, the X-ray source emits X-rays to an object, and a cassette detects the X-rays transmitted through the object to take an image. Based on data of taken plural images, tomographic image, which puts emphasis on a region of interest inside the object, is produced.