Benthic animal community in the northernmost mangrove forest of southern Kyushu was investigated compared with that in the mangrove forest of Amami Island. The latter is in subtropical area, while the former is in temperate area, out of natural distribution area of mangrove trees. We expected that the utilization of this habitat by benthic animals might be different between temperate area and subtropical area. From 2 to 6 sampling points were placed along the lines set perpendicular to the river. Benthic animals were sampled by using 1 mm meshed sand strainer from the sediment, which　was collected by using 17cm diameter core. We compared benthic fauna in the mangrove forest with that in the neighboring mud flat. Qualitative similarity of benthic animal community between two habitats was higher in temperate area than in subtropical area. However, the cluster analysis with quantitative data indicated that benthic animal community in mangrove forest was similar to that of mud flat in subtropical area. We got the opposite result in temperate area. It was caused by that the dominant species was different between two habitats in temperate area, while both were dominated by Ilyoplax pusilla in subtropical area. These results suggest that many species inhabited both in mangrove forest and mud flat in temperate area, though their densities were different between habitats.