1. An image processing apparatus comprising: a first memory configured to store a desired volume three-dimensional image; a second memory configured to store a sequentially updated two-dimensional image; a processor configured to align the three-dimensional image with the two-dimensional image, to acquire a position of a device, and to calculate the distal end position of the device in the three-dimensional image; and a display configured to display the three-dimensional image and a sectional image of the three-dimensional image including the position of the device, wherein the display further is configured to display, in the three-dimensional image, a mark indicating three-dimensional coordinates of the position of the device; a position of the mark in the three-dimensional image is updated per heartbeat; and the sectional image is updated per heartbeat.