An endoscope system includes a correction-value calculating unit that calculates a correction value of data to be used for calculation of the biological information or the like; an index-value calculating unit that calculates one type of index value or a plurality of types of index values to be used as a determination reference for determining whether, for example, the correction value is to be calculated; a determination unit that determines, by using the one type of index value or the plurality of types of index values, whether an endoscope image is appropriate for correction; and a correction unit that, if the determination unit determines that the endoscope image is appropriate for correction, corrects the endoscope image, the biological information, or the data by using the correction value calculated by using the endoscope image that has been determined to be appropriate for correction.