1. A force vector reconstruction method that uses an optical tactile sensor, said sensor having a tactile portion comprising a transparent elastic body and a plurality of marker groups provided in said body, each marker group being comprised of a number of colored markers, with markers constituting different marker groups having different colors for each group, said method comprising the steps of: obtaining a marker image by taking an image of behavior of colored markers when an object contacts a contact surface of the elastic body; obtaining information relating to the marker behavior from the marker image, said information being more than the number of force vectors to be obtained; and obtaining force vectors as outputs by inputting said obtained information relating to the marker behavior to a transfer function, wherein said obtaining force vectors calculates force vectors omitting information relating to behavior of the marker that has low extent of contribution to force vector calculation.