The Furuhama Park, which was improved and developed artificially in 2004 at Heiwajima artificial island of Ota City, is located at the innermost part of Tokyo Bay. The Park is composed of the tidal flat（1ha）and sandy beach（1.2ha）in east and west, respectively, with a shallow water area（4.6ha）between them, and separated from the outside canal by submerged dikes. Monthly samplings of fishes were carried out in both the tidal flat and sandy beach by using the small seine-net from May 2014 to June 2015. A total of 31,736 individuals representing 35
species of 18 families were collected, almost all of them being larvae or juveniles. No remarkable differences were detected between the tidal flat and sandy beach from the viewpoint of numbers of species and individuals per towing and species compositions. Three gobiids, Acanthogobius flavimanus, A. lactipes and Gymnogobius breunigii, were determined as resident species. The numbers of marine fishes and ayu Plecoglossus altivelis altivelis, usually drifted by tidal/shore currents and being dominant at shorelines of the inner Tokyo Bay in summer and winter, respectively, were relatively low when comparing with other areas. This study suggested that the Furuhama Park would provide diverse habitats for estuarine fishes, but the insufficient water circulation would make the Park unsuitable habitats for marine fishes.