An X-ray CT apparatus includes a host and a scanner that executes a scan based on a scan program communicated from the host by means of communicating means. The X-ray CT apparatus also includes a communicating means which collectively communicate the calculated values of X-ray applied amounts at every scan positions or original data for the calculation of the amount of X-ray application even with respect to unprogrammed scan positions. Each of the calculated values of X-ray applied amounts corresponds to a tube current value of an X-ray tube. The original data for the calculation of the amount of X-ray application corresponds to X-ray penetrated image data of a subject.