1. An endoscope apparatus comprising: an image pickup portion that picks up an image of an object; and a measurement portion that measures the object based on the image of the object obtained by the image pickup portion, wherein the measurement portion comprises: a specification portion that specifies three base points on the image; a composing point calculation portion that calculates composing points forming an object region of the object, based on an image region that is based on a plurality of points, the points set on a line determined by the three base points that are specified by the specification portion; and a size calculation portion that calculates a size of the object based on the composing points.