A storage unit stores data of a blood vessel image, a first mask image, and a second mask image of an object, an imaging unit which images a fluoroscopic image for the object. A subtraction unit subtracts the first mask image from the fluoroscopic image and generates data of a subtraction image. A calculating unit calculates anatomical displacement amount between the first mask image and the second mask image. A display unit displays the blood vessel image and the subtraction image so as to be superimposed each other by positioning the blood vessel image and the subtraction image to be fitted together on the basis of the calculated displacement amount.