As a result of our morphological study on Pseudogloiophloea okamurai, the following characteristics are described: 1) Thallus structure is of the so-called fountaintype. 2) The outermost layer of the thallus consists of large non-colored vesicular cells and small colored cells. 3) The plant is unisexual. 4) The male reproductive organ (spermatangium) is borne terminally on a cortical filament arising from a medullary filament. 5) Spermatangia are scattered in groups over the surface of the thallus, resulting in a patched appearance. 6) The female reproductive organ (carpogonium) is borne terminally on a cell of a cortical filament near the surface, close to the growing point. The initial of a carpogonial branch is generally formed between the bases of forked branches. 7) The carpogonial branch is three- celled prior to fertilization. 8) Prior to fertilization, the first cell of a carpogonial branch cuts off sterile cells which, after fertilization, give rise to branched filaments forming a pericarp. 9) The second cell of a carpogonial branch (the cell below the carpogonium) undergoes vertical cell divisions prior to fertilization and gives rise to four hypogynous cells. 10) After fertilization, the carpogonium becomes reduced in size and content, resulting in a faded appendage on one of the hypogynous cells. On the other hand, the four hypogynous cells increase both in size and content, resulting in much enlarged bodies, which are probably involved in nutrition of the zygote nucleus. 11) The gonimoblast initial is produced from the faded carpogonium. The portion from which the initial is cut off is closest to the hypogynous cell connected with the carpogonium. 12) The gonimoblasts produce carposporangia terminally, which are in chain of 2-4 cells. 13) Carpospores are spherical, measuring 8-10μ in diameter, and undergo germination of the “indirect filamentous type”.