A new brackish-water species of melitid amphipod, Melita choshigawaensis, from the Choshigawa River, Mie Prefecture, Japan, is named and described. Melita choshigawaensis sp. n. is distinguished from the most similar M. shimizui (Uéno, 1940) by having an elongate and weakly arched male uropod 3, and a deep and strongly hooked anterior lobe of the coxa on the female's pereopod 6. Nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I (COI) of M. choshigawaensis and M. shimizui support divergence at the species level. A key to the Japanese species of Melita is provided.