We describe Hedgpethia spinosa sp. n. based on a single male specimen obtained from 197–207 m depth, south of Yaku Island, Kagoshima Prefecture, Japan. Among 15 previously known congeners, the new species resembles H. bicornis (Losina-Losinsky & Turpaeva, 1958), H. chitinosa (Hilton, 1943), and probably H. brevitarsis (Losina-Losinsky & Turpaeva, 1958), ina mid-dorsal tubercle on the posterior rim on each trunk segment. The new species, however, is distinguishable from those by a pair of horns on the anterior margin of the cephalic segment, spines on the first coxae, and denticulate spines on the strigilis. The new species represents the fifth member of the genus so far known from Japanese waters, in addition to H. brevitarsis (Losina-Losinsky & Turpaeva, 1958), H. chitinosa (Hilton, 1943), H. dofleini (Loman, 1911), and H. elongata Takahashi, Dick & Mawatari, 2007.