This invention provides a compact X-ray CT system capable of obtaining an X-ray CT image having high resolution at a high speed by deflecting a predetermined electron beam and causing the finely focused electron beam to scan on an arcuate anode target inside the same plane as the arcuate anode target for an X-ray source. The anode target for an X-ray source and a detector are disposed in the form of arcs inside substantially the same plane so as to face each other. The electron beam emitted from an electron gun is guided to a deflector through a lens system, is then deflected to a arc form trajectory by a uniform magnetic field generated by the deflector and is guided to the anode target after a reverse magnetic field is applied to the electron beam at a desired position. This electron beam is caused to scan on the anode target at a high speed so as to move the generation position of the X-ray and thus to obtain a sectional image.