An X-ray CT apparatus has an image generating unit and a blood flow information acquiring unit. The image generating unit acquires projection data at rest and at non-rest from a myocardial part of an object into which contrast medium is injected continuously in a state in which each concentration of the contrast medium can be considered to be constant and reconstructs contrast CT image data at the rest and at the non-rest using the acquired projection data. The blood flow information acquiring unit obtains third blood flow information based in first blood flow information derived from the contrast CT image data at the rest and second blood flow information derived from the contrast CT image data at the non-rest.