An image processing apparatus includes a memory unit which stores data of a first projection image and data of a second projection image, which are associated with the same object and are captured in different imaging directions, a display unit which displays the data of the first projection image and the data of the second projection image, a designation operation unit which is configured to designate a plurality of points on the displayed first and second projection images, and an operation supporting unit which generates operation supporting information for supporting an operation of designating, by the designation operation unit, the plurality of points on the second image, which anatomically correspond to the plurality of points designated on the first projection image.