In order to assess ecologically for the restored detention basin in Joogyo creek, this study carried out a monitoring on the ecosystem of the detention basin. The study site was a small detention basin with an area $6,350m^2$, which had been established in March, 2004. The monitoring started in August and November, 2007. Terrestrial, riparian, and aquatic plants species have increased about 2 times at detention basin compared to that of streamside. Mammals, birds, reptiles, amphibians, aquatic insects and crustaceans were found more in species at detention basin, and especially there were a lot of more fish species. From the results, it seemed that various terrestrial, riparian, and aquatic ecosystem were made in the small detention basin.