In this study, we histologically investigated the late stage of oogenesis, spermatogenesis, and pseudo-egg development processes of the pseudo-dioecious coral Galaxea fascicularis to form a base from which to elucidate the mechanisms of coral sexual reproduction. This coral has a large egg size and individual polyps, which are suitable for studying the mechanism of sexual reproduction. The histological analysis revealed that germinal vesicle breakdown of this coral begins 3 days before spawning in both female oocytes and male pseudo-oocytes. Spermatogonium, spermatocytes, spermatids, and sperm were observed in the male testicular lobules from 2 months to 1 day before spawning. The findings of our study might allow for the elucidation of the mecha-nisms of sexual reproduction in this species and facilitate the development of methods for its aquaculture.