A member of mice interferon inducible transmembrane protein like family, IFITM1, is reported to play an important role in primordial germ cell (PGC) formation and this protein reported for anti‐proliferation. This study conducted to investigate the mIFITM1 expression in reproductive organs of male mice. mIFITM1 expression in testis and epididymis were revealed by immunostaining and immuno blot. Moreover, we showed that mIFITM1 is related to development of mouse testis. mIFITM1 protein expression as markedly upregulated around 5‐ 15day after birth in testis, but postnatal 21 56 day detected pattern was decreasing by immunoblot. In the other reproductive organ, epididymis, we observed that mIFITM1 protein was strongly expressed in caput, corpus and cauda. We analyzed IFITM1 gene expression under conditions of androgen manipulation. Total RNAs were obtained from the epididymis of adult mice that castrated and injected. Testosterone replacement for animals 7day after surgery. In castrated animals, A clear decrease was found in the IFITM1 protein level on Interestingly, castrated mice was revealed that mIFITM1 expression is strong. At that time, the injected catration mice decrease in IFITM1 gene expression. We also found same result from the immunoblot analysis. Our data suggest that the function of the IFITM1 expression in sperm is remain unclear but mIFITM1 expression will be important to postnatal development of mice testis and spermatogenesis. Also, mIFITM1 regulated not only sexual maturation by gene expression in the reproductive organs but also by hormone.