1. A measurement method using an 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 carries out a procedure of measuring the measurement object based on the image signal, the method comprising: designating two reference points on the measurement object; calculating an approximate outline by approximating the outline of the measurement object based on the reference points; calculating loss-composing points that constitute the outline of a loss formed on the measurement object based on the reference points and the approximate outline.