PROBLEM TO BE SOLVED: To provide X-ray CT equipment, in which the number of signal lines between a multislice X-ray detector and a preamplifier unit is reduced, and in which leakage of a noise mixed with the detection signal of the X-ray detector from a switch changeover signal used to change the slice width is eliminated. SOLUTION: An X-ray detecting element group comprises a scintillator 3, a light-detecting element array 2 which has a light-receiving region, separated into a channel direction and a slice direction and a switching element array 4, in which a plurality of outputs from the light-receiving regions separated into the slice direction are changed over and guided to an external circuit the X-ray detecting element group is mounted on a board 1 a plurality of X-ray detecting element groups are arranged in a polygonal shape, at nearly equal angle pitches on an approximate arc, which uses an X-ray-tube focus as the center and thereby, the X-ray detector is constituted. When the X-ray detector is used for a multislice X-ray CT equipment, a plurality of tomograms of high image quality are obtained with a single scanning operation.
