PROBLEM TO BE SOLVED: To develop a Fenton reaction catalyst which is harmless to a human body or an environment, and which can maintain bivalent iron stably for an extended period.SOLUTION: There is provided a Fenton reaction catalyst in which a reaction product obtained by mixing a prescribed reducing organic matter (plant body dry distillation liquid component) with an iron feedstock at a prescribed ratio in the presence of water is used as an active ingredient. Further, there are provided a sterilization method, a pollutant decomposition method, and a luminescence method utilizing chemiluminescence, in which the Fenton reaction catalyst is used.SELECTED DRAWING: Figure 2