Provided is an X-ray CT apparatus which can perform CT scan of multi-energy scanning at a high speed and can obtain an image having an excellent substance distinguishing ability. The X-ray CT apparatus includes: means to continuously perform a first CT scanning using a first X-ray energy and a second CT scanning using a second X-ray energy without interrupting CT scan means to transit the X-ray energy emitted from the X-ray during a transition period TR including an end of the first CT scanning and a beginning of the second CT scanning from the first X-ray energy to the second X-ray energy and means to compensate the scan data in the transition period by the opposing data in the residual scan period so as to reconstruct an image.
