The lamination of the masseter muscle was gross anatomically examined in the water deer (Hydropotes inermis). We could distinguish several layers such as the M. masseter superficialis, M. masseter intermedius, M. masseter profundus, M. maxillo-mandibularis, and M. zygomaticomandibularis, The M. masseter superficialis was subdivided into lamina prima and lamina secunda. The lamina prima originated from the facial tuber, facial crest, and zygomatic arch with a broad tendinous sheet. The lamina secunda arose from the posterior facial crest and anterior area of the zygomatic arch and was inserted to the mandible by a broad tendinous sheet. The M. masseter intermedius arose from approximately same origin as the superficialis lamina secunda by a distinct tendinous sheet. Moreover, only one part was confirmed in the M. maxillo-mandibularis and the M. zygomatico-mandibularis and only two parts in the M. masseter profundus pars posterior. Moreover, the most rostral part of the M. maxillo-mandibularis was inserted to the mandible by a small weak tendon. This result suggests that this muscle layer may not restrict the mouth opening more remarkably than that of cervids which develop the tendon. In this study, we could confirm the lamination of the masseter muscle with the simplified layers in the water deer.