X-ray ct apparatus and the correction processing unit

To provide a technology for reducing the system noise from the output signal value (measurement data), and the X-ray generator for irradiating X-rays to the subject, and the X-ray detector for detecting X-rays transmitted through the subject, a correction processing unit for correcting the output signal of the X-ray detector, an X-ray CT apparatus and a reconstruction operation unit for reconstructing an image from the output of the correction processing unit, the X-ray detector, comprises a sequence has been detected element, the correction processing unit, while maintaining the average value of the output signal value of a predetermined plurality of detection elements centered on the detector elements focused among the detecting elements, the target was detected element reducing the predetermined variance of the output signal values ​​of a plurality of detection elements centered on.