An image processing apparatus includes a storage unit which stores the data of a plurality of images in an angiography sequence, and a computation unit which generates a reference time density curve concerning a reference region set in a blood supply region to a blood supplied region and a plurality of time density curves concerning a plurality of local regions set in the blood supplied region on the basis of the data of a plurality of images, and computes a plurality of indexes respectively representing the correlations of the plurality of time density curves with respect to the reference time density curve.