To provide a method and system for sterilizing the surface of a space which efficiently sterilizes the surface of a space by inexpensive equipment, the method and device being safe to a human body and effective for spore bacillus sterilization and dispensing with the high-level shielding of a sterilization space.

A sterilizer adjusted to a low-concentration being hydrogen peroxide solution having a concentration of 1-10 wt.%, peracetic acid solution having a concentration of 0.1-1 wt.%, or hypochlorous acid solution having a concentration of 0.01-0.1 wt.% is atomized and sprayed to the sterilization space to be attached. Thereafter, the humidity in the sterilization space is adjusted to dry the sterilizer by drying with air, so that high-level sterilization is performed speedily and inexpensively.