PROBLEM TO BE SOLVED: To provide an organic deoxidation agent containing tannin or a tannic acid as a main agent and capable of exhibiting a sufficient deoxidation performance even at a low temperature.SOLUTION: An organic deoxidation agent contains tannin or a tannic acid as main agents, alkali agent and water, and is characterized by containing triethanolamine within a range of 0.5 weight parts to 55 weight parts with respect 100 weight parts of main agent.SELECTED DRAWING: None