PROBLEM TO BE SOLVED: To provide an odor suppression method and an odor suppression composition for an odor-emitting material that can suppress the odor derived from hydrogen sulfide or methyl mercaptan or the like produced by the microorganism activity, for a long period of time and that relatively has a low toxicity and that is inexpensive.SOLUTION: The odor emitted from an odor-emitting material is suppressed by adding, to the odor emitting-material, nitric acid or a salt thereof (nitric acid-based substance) and at least one (disinfectant-based substance) selected from a group consisting of imidazole or a salt thereof, 2-bromo-2-nitro-propane-1,3-diol, hydroxylamine or a salt thereof, and tetrakis (hydroxymethyl phosphonium salt. In this case, the nitric acid-based substance and the disinfectant-based substance are added into the odor-emitting material in such away that the concentration of the nitric acid-based substance in the odor-emitting material is 50 to 1000 mg/L in terms of nitric acid ion concentration and also the concentration of the disinfectant-based substance in the odor-emitting material is 5 to 300 mg/L.
