An endoscope system, includes a light source device that emits illumination light to an object, an image obtaining part that captures light reflected at the object by an image pickup element and thereby obtains a color image including at least three color components, and an evaluation part that obtains, for each of pixels constituting the color image obtained by the image obtaining part, an evaluation result concerning a target disease based on an angle, in a color plane being defined by at least two of the at least three color components, formed between a line segment, which connects a predetermined reference point positioned on the color plane with a corresponding pixel point allocated corresponding to the each of the pixels in the color plane, and a reference axis having a correlation with the target disease. The reference axis is set to pass through the predetermined reference point.
