Abstract: Genomic DNA region including the about 1.5 kb upstream region of MEGSIN gene was isolated and its nucleotide sequence was determined. In the genomic DNA region, two regulatory sequences that regulate the transcription positively were identified. Furthermore, nucleotide substitutions were introduced in the promoter regions located at the 3′ sites of the two regulatory sequences by site specific mutagenesis, and the nucleotide sequences that play important roles in the promoter activity were successfully identified.