An information processing system (10) comprises: a distance acquisition unit (110) that specifies an iris area containing an iris of a target from a visible-light image of the target, and acquires an iris distance that is a distance to the iris area; an iris image acquisition unit (120) that acquires an iris image of the target by changing a focal length according to the iris distance; a score computing unit (130) that calculates a score relating to deviation of a focus in the iris image, based on the iris image; and a correlation update unit (140) that updates correlation between the iris distance and the focal length at a moment of acquisition of the iris image, based on the score. According to such an information processing system, since the correlation is updated with good accuracy, it is possible to acquire the appropriate iris image.