PROBLEM TO BE SOLVED: To determine whether or not a user read a sentence even when accuracy of sight line position coordinates outputted from a sight line detection device is low.SOLUTION: An information processor includes: means which acquires a sight line position on a display screen (A); and determination means which counts the number of times of movement of a sight line position expressing line feed in a second region defined based on a first region surrounding character strings on the display screen, determines whether or not the counted number of times becomes equal to or greater than a threshold defined according to the number of lines in a reading direction of the character strings included in the first region, and if the number of times becomes equal to or greater than the threshold, stores data expressing "already read" for the first region in a data storage section (B).
