An object of the present invention is to provide an image processing technology capable of perceiving a motion of the shape of a target area. An image processing device (3) according to the present invention includes: a dynamic image acquiring unit (110) that acquires a dynamic image; a boundary line extracting means (130) that acquires a plurality of target area boundary lines by extracting boundary lines of a target area; a displacement correcting means (140) that acquires a predetermined number of displacement-corrected boundary lines in which a removal-required component is removed by calculating a displacement amount, which is the removal-required component, using a base boundary line as a displacement base for one or more of target area boundary lines other than the base boundary line among the plurality of target area boundary lines by using pixels corresponding to the plurality of target area boundary lines and correcting a predetermined number of the target area boundary lines other than the base boundary line by using the displacement amount after the calculation of the displacement amount; and a display means (34) that displays displacement-corrected boundary line information for display based on the predetermined number of displacement-corrected boundary lines.