In May and June 2018, we collected both benthic and drifting large brown algae Sargassum horneri on the coast of Takehara City, Hiroshima Prefecture, Japan. The animal communities on benthic and drifting thalli were compared. Phytal animals such as harpacticoid copepods, amphipods, isopods, and polychaetes were predominantly found on both thalli. The Horn’s overlap index showed that the animal communities on drifting thalli in June 2018 were clearly different from those of the benthic thalli.