A three-dimensional image processing apparatus includes a three-dimensional image acquisition unit that acquires a three-dimensional image obtained by imaging a test object； a graphical structure generation unit that generates a graphical structure of a tubular structure included in the three-dimensional image； a contour information acquisition unit that acquires contour information on the tubular structure at each point on the graphical structure； a viewpoint information acquisition unit that acquires viewpoint information in the tubular structure； a projection point specification unit that specifies projection points from respective points on the graphical structure on the basis of the viewpoint information and the graphical structure； and a projection image generation unit that generates a projection image obtained by projecting the contour information at the projection points on a two-dimensional plane.
