1. A measurement method using an endoscope apparatus, the endoscope apparatus comprising an electronic endoscope that picks up a measurement object and produces a picked-up-image signal, an image-processing unit that produces an image signal based on the picked-up-image signal, and a measurement processing unit that measures the measurement object based on the image signal, the method being implemented by the endoscope apparatus to perform functions comprising: designating two reference points on the measurement object; calculating an approximate outline by approximating an outline of the measurement object based on the two reference points; and calculating loss-composing points that constitute the outline of a loss formed on the measurement object based on the two reference points and the approximate outline; wherein the two reference points are designated such that the loss formed on the measurement object is interposed between the two reference points.