1. An anterior segment three-dimensional image processing apparatus that receives and processes an anterior segment three-dimensional image of a subject's eye by means of an optical coherence tomography device, the apparatus comprising: a first SS position specifying unit that accepts identification of at least three SS positions indicating a spatial coordinate position of a scleral spur of the subject's eye, using at least two representative images from among a plurality of two-dimensional tomographic images constituting the anterior segment three-dimensional image; a true circle calculating unit that calculates a reference true circle passing through the at least three SS positions of the SS positions identified by the first SS position specifying unit in the anterior segment three-dimensional image; and a second SS position specifying unit that identifies the SS positions in non-representative images other than the representative images from among the plurality of two-dimensional tomographic images, based on the reference true circle calculated by the true circle calculating unit.