A character pattern extracting method includes ranking character patterns whose number is larger than a maximum number of character patterns in an aperture, depending on the number of reference times in design data of a semiconductor device, extracting first extraction patterns whose number is smaller than the maximum number from the large number of read character patterns in a descending order of the reference time number, defining character patterns except the first extraction patterns out of the larger number of character patterns as candidate patterns, selecting from the candidate patterns a plurality of candidate patterns whose number corresponds to a difference between the number of extracted patterns from the maximum number, and creating combinations of the selected candidate patterns, and extracting second extraction patterns included in a combination among the combinations of candidate patterns, in which a manufacturing time of the semiconductor device is most shortened.