An endoscope system includes an illumination section that radiates illumination light and illuminates a predetermined illumination range, an image pickup section that picks up an image of a predetermined image pickup range of a subject illuminated by the illumination section, a low-luminance-portion detecting section that detects a low luminance portion in the picked-up image of the subject picked up by the image pickup section, and a convex-portion-size detecting section that detects a convex portion in a predetermined size range on the basis of information concerning the low luminance portion detected by the low-luminance-portion detecting section.
