When there is a possibility that a third character region is redundantly selected in both a case where the line extraction process is performed starting from a first character region and a case where the line extraction process is performed starting from a second character region located in a line different from a line containing the first character region, the line recognition unit determines which line to incorporate the third character region in, by comparing a case of incorporating the third character region into the line starting with the first character region, with a case of incorporating the third character region into the line starting with the second character region.