A new eusirid amphipod, Rhachotropis lowryi sp. nov., is described from off Amamioshima Island, Japan, at 402 m depth. This new species differs from its congeners by the features of urosomite 1, pereopods 5–7 bases, uropod 3, and telson. A key to species of Rhachotropis from Japanese and adjacent waters is provided. Additionally, a nucleotide sequence of mitochondrial cytochrome c oxidase subunit I from the holotype of R. lowryi was determined for the future study.