1. A lithography apparatus for writing a pattern on an exposure mask using a charged particle beam, comprising: an interpreter unit configured, by receiving a data file including character information which uses at least one of letter and numeral and specifies a shape of an identification figure representing identification information of the exposure mask before pattern writing process, to interpret contents of the character information; a generating unit configured, by receiving the character information, to generate pattern writing data of the identification figure on the basis of the character information in a same format as that of a pattern writing data of a pattern written on the exposure mask after the contents of the character information is interpreted; a synthesizing unit configured, by receiving the pattern writing data of the pattern written on the exposure mask, to synthesize the pattern writing data of the pattern and the pattern writing data of the identification figure; a verifying unit configured, by receiving frame information of the pattern written on the exposure mask, to verify whether the identification figure overlaps the pattern on the basis of the character information and the frame information of the pattern in a case that the identification figure and the pattern are written on the exposure mask using a charged particle beam; a correcting unit configured to selectively correct a reference position and a size of the identification figure when the identification figure overlaps the pattern in the case; and a pattern writing unit configured to write the pattern and the identification figure on the exposure mask on the basis of the synthesized pattern writing data in a case that it has been verified that the identification figure does not overlap, using a charged particle beam.