Abstract:The very rare species of sicydiine gobiid genus, Lentipes Günther, 1861 has been found first time from Taiwanese waters. The species can be identified as Lentipes armatus Sakai and Nakamura, 1979 previously proposed as Japanese endemic species, and was listed in the 5-star ranking red-list as one critically endangered species of Japan. The diagnosis and redescription of current species from Taiwanese and Japanese specimens are reported herein. The distribution range of current rare species extends to Taiwan including Lanyu (Orchid island) off eastern coast proved that this species is not Japanese endemic. The morphological comparison of Taiwan and Japanese populations are indistinct except a few meristic counts.