1. A three-dimensional image construction apparatus comprising: a display unit displaying a first three-dimensional image on a predetermined origin surface; an input unit receiving an input of a region of interest for a second three-dimensional image in the first three-dimensional image; and a calculation unit setting the origin surface as an initial value of the origin of a projection line to construct the second three-dimensional image, correcting the origin of the projection line for a pixel in the region of interest based on a depth image corresponding to the first three-dimensional image, and then constructing the second three-dimensional image using the corrected origin of the projection line for the region of the interest.