PROBLEM TO BE SOLVED: To provide an ophthalmologic apparatus which accurately measures a layer thickness of an acquired tomogram image.SOLUTION: A direction of measuring a layer thickness is determined based on a shape of a layer boundary of a retina, and the layer thickness is measured along the direction. By this, even when the retina is greatly inclined or curved, the layer thickness can be measured accurately. Thus, flatness of the retina is calculated from a shape of RPE, and a measurement method of the layer thickness is determined. A measurement direction vector of the layer thickness on a plurality of reference points set on the RPE (retinal pigment epithelium) is calculated, and an intersection point of an ILM (inner limiting membrane) and these vectors is found. A distance from the reference point to the intersection point is equal to the layer thickness at each reference point. By measuring the layer thickness in this way, it is possible to perform the highly accurate measurement of the layer thickness with which the shape of the retina is considered.
