The genus Eulophias, which is an enigmatic group of the suborder Zoarcoidei, previously comprised two rare species: Eulophias tanneri Smith, 1902 (type species and a senior synonym of Eulophias owashii Okada and Suzuki, 1954) and Eulophias koreanus Kwun and Kim, 2012. Here we describe a new species, Eulophias spinosior, based on 71 specimens (94.9–182.3 mm in standard length, SL) collected from the upper slope of the northwestern Pacific off southern Japan at depths of 257–555 m. It readily differs from its two congeners in having 133–143 dorsal-fin spines, 109–116 anal-fin soft rays, 5–6 pectoral-fin rays, and 146–156 total vertebrae, and in lacking a dark band posterior to the eye and a series of dark blotches midlaterally on the trunk and tail. Regarding bathymetric distribution, the new species occurs much deeper than E. koreanus and E. tanneri. Eulophias spinosior, new species, is sexually dimorphic, with males having large, stout, modified canines at the tips of the premaxillary and dentary (vs. only slightly enlarged in females). Dentition of males also differs from that of females in that most teeth are uniserially arranged in each jaw (vs. distinct two rows anteriorly).