An image processing apparatus includes a storage unit which stores data of X-ray projection images generated through a angiographic imaging sequence, a generation unit which, based on the data, generates a reference time density curve concerning a reference region which is set as a blood supply region, and time density curves concerning perfusion regions which are set as a blood supplied region, a measurement unit which measures delay times for which a contrast medium reaches the perfusion regions from the reference region, from relationships between the reference time density curve and the time density curves, a calculation unit which calculates, respectively for the perfusion regions, first indices expressing correlations of the time density curves to the reference time density curve within a period determined on the basis of the delay times, and a first image generation unit which generates a first image expressing spatial distribution of the first indices.
