̶ A new species of Bathyceradocus, one of the maerid amphipods, is described based on the specimens collected from sunken wood on the bottom of the Kumano-nada, central Japan. Bathyceradocus japonicus sp. nov. can be distinguished from its congeners by the number of the accessory spines on the pleonite 1, the number of articles on the accessory flagellum, and the strongly oblique palm of the gnathopod 2 with the dentate margin. A brief note on the behavior of the new species and a key to species of the genus are provided.