Abstract: A method of separating and recovering 18F from 18O water at high purity and efficiency while maintaining the purity of the 18O water. By using a solid electrode (1) as an anode and a container (electrodeposition vessel) (2) made of platinum as a cathode, 18F in a solution (4) is electrodeposited on the solid electrode surface by applying a voltage. Then, by using the solid electrode (1) on which 18F is electrodeposited as a cathode and a container (recovery vessel) (5) holding pure water therein as an anode, 18F is recovered in the pure water by applying a voltage of opposite polarity to that of the electrodeposition. In this process, little 18O water is lost. The initial concentration of the 18O water is maintained even after the electrodeposition of 18F, so that the 18O water can be repeatedly used as an irradiation target for production of 18F.