In order to understand the amount of elution of nutrients from the sediment, which is important when considering the environment of the Seto Inland Sea, elution data and environmental data were collected from existing literature. We tried to estimate the elution amount of nutrients from the three items of water temperature, dissolved oxygen concentration in the bottom layer, and amount of organic matter in the bottom layer. Total organic carbon and ignition loss were used as indicators of the amount of sediment organic matter, and the estimated nutrients were dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). From the prepared formula and the environmental data of the Seto Inland Sea, the elution amount of DIN and DIP in the entire Seto Inland Sea was estimated. The elution amount in the entire Seto Inland Sea increased from around 1980 and then began to decrease, and by around 2015 it was lower than around 1980. It was suggested that the decrease in elution amount of entire Seto Inland Sea in recent years is largely due to the decrease in elution amount in the sea area where the elution amount is large.