An X-ray computed tomography apparatus scans a subject to be examined with cone beam X-rays, and generates reference volume data on the basis of projection data (SA1)- This apparatus extracts a cone beam artifact component contained in the reference volume data on the basis of the typical shape and direction of the cone beam artifact component (SA2, SA3, SA4, SA5, and SA6). This apparatus generates resultant volume data with the reduced cone beam artifact by subtracting the cone beam artifact component from the reference volume data (SA7).
