CHARACTER STRING INPUT APPARATUS, INPUT CHARACTER STRING INFERENCE METHOD, AND INPUT CHARACTER STRING PRESUMPTION PROGRAM

A character string input apparatus has a display unit that displays a keypad image in which a plurality of character keys are arranged, on a screen of a display device, an operation position detector that detects pressed positions on the screen of the display device, a score calculator that calculates, for each of the character keys of the keypad image, scores of the pressed positions on the screen of the display device, a score data generator that generates, for each of the pressed positions on the screen of the display device detected by the operation position detector during a character string input period, score data in which the scores for the character keys calculated by the score calculator are registered, and an input character string inference unit that infers a character string that was input, using the score data generated by the score data generator.