PROBLEM TO BE SOLVED: To provide a medical image processor capable of removing unerased remains (artifact) other than a blood vessel due to a three-dimensional movement from a difference image even though the movement of a subject exists.SOLUTION: The medical image processor of this embodiment includes a difference image generation part for performing difference processing of a mask image picked up before inputting a contrast medium into a subject and a contrast image picked up after inputting the contrast medium to generate a difference image, a white and black pair determination part for determining whether a pair of a white part and a black part exists within the predetermined range of the difference image when a part in which a pixel value is higher than a prescribed first threshold is made to be the white part and a part in which a pixel value is lower than a prescribed second threshold is made to be the black part on the difference image, and a removal processing part for removing pixels of the white part from the difference image in the case that the pair of a white part and a black part exists.
