An information processing system for performing processes on first image and second image captured from different viewpoints, comprising: a first specifying part for specifying a first corresponding point on the second image, corresponding to a designation point designated on the first image, by searching on a line along a first basis direction corresponding to a predetermined direction and passing through a position corresponding to the designation point in the second image; a second specifying part for specifying a second corresponding point on the second image, corresponding to the designation point, by searching on a line passing through the first corresponding point in the second image and along a second basis direction almost perpendicular to the first basis direction; and a third specifying part for specifying a third corresponding point on the second image, corresponding to the designation point, by searching on a line passing through the second corresponding point in the second image and along the first basis direction.