There are provided an endoscopic diagnosis apparatus, image processing method, and a non-transitory computer-readable recording medium that enable easy measurement of the size of a lesion portion or the like based on an endoscopic image captured through a normal operation without a special operation. A region detecting unit detects, from a position in an endoscopic image, a region having a periodic structure of living tissue. An imaging size calculating unit calculates, in number of pixels, an imaging size in the endoscopic image equivalent to a period in the periodic structure in the region having the periodic structure. A pixel size calculating unit calculates an actual size corresponding to one pixel of the endoscopic image. A scale generating unit generates scales indicating an actual size of the subject in the endoscopic image. A control unit causes the endoscopic image and the scales to be combined and displayed on a display unit.
