During his journey in July-August of 1962, the present writer made some investigations on the fresh-water shrimps and prawns of the tree islands of Satsunan group, viz. Amami-oshima, Yaku-shima and Tanega-shima. The present paper deals with those animals collected by this writer himself and others. Those species may be given below : Atyidae −Parataya compressa, Caridina typus, C. japonica, C. leucosticta, C. serratirostris, Palaemonidae− Paramon paucidens, Macrobranchium longipes, M. japonicum. Among these fresh-water species, C. typus was obtained most abundantly, accordingly it appears that the species is the most dominant one at least in the islands in which the conections have been made. The fresh-water shrimp and prawn fauna of these islands much resemble those of Kyushu, Shikoku, and the South-western part of Honshu, Japan, but differ from those of Okinawa Island.