A printing system includes a printing unit, a position determiner that randomly determines a position where a first information code is to be set, a modifier that modifies print data for printing an image, the first information code, and a positional information code having recorded therein positional information at the time of printing that indicates the position determined by the position determiner so that the first information code is set at the position determined by the position determiner, an acquirer that acquires the position of the first information code on a print medium as positional information and acquires the positional information at the time of the printing from the positional information code, and a determiner that determines whether the printing result is a falsified matter based on comparison of the positional information after the printing with the positional information at the time of the printing.