PROBLEM TO BE SOLVED: To provide a drug effect prediction method enabling space designing that can elicit the effect of a sterilization system.SOLUTION: The drug effect prediction method consists of an acquisition step (S105) of verification effect for each spraying condition by repeating an actual installation step (S102) of placing test bacteria at a predetermined position in a real space under multiple spray conditions and a verification step (S103) of spraying a predetermined drug in the real space to verify the drug spray effect against the test bacteria at the predetermined position； an acquisition step (S109) of a concentration-time integration value for each spraying condition by repeating a concentration-time integration value calculation step (S107) of calculating the concentration-time integration value of the drug on a basis of an airflow analysis step (S106) at the predetermined position and the concentration-time integration value calculation step under a plurality of spray conditions； and a minimum spray condition acquisition step (S110) of acquiring the lowest spraying condition at which the drug acts effectively against the test bacteria at the predetermined position by associating the acquired verification effect for each spraying condition with the acquired concentration-time integration value.SELECTED DRAWING: Figure 3
