PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of reducing unnecessary exposure in a helical shuttle scan.SOLUTION: An X-ray CT apparatus performs an X-ray scan by an X-ray scan section, collects detection data while causing a top board and the X-ray scan section to relatively reciprocate in a first direction parallel to a longitudinal direction of the top board and in a second direction that is an opposite direction thereto and generates an image of a body to be inspected on the basis of the detection data collected. The X-ray CT apparatus has a calculation section, a comparison section and a control section. The calculation section corresponds to a predetermined state of a scan in the first direction and calculates a required period of time until a scan in the second direction continuously performed subsequent to the scan in the first direction is started. The comparison section compares the required period of time calculated and a preset period of time to start up an X-ray generation section. The control section controls the X-ray generation section on the basis of comparison results by the comparison section.
