An apparatus for sterilizing and disinfecting a target space by spraying a chemical including alcohol includes a spray gun to which a chemical container containing a sterilizing and disinfecting chemical including alcohol is attachable, a gas cylinder filled with a compressed carrier gas that does not react with alcohol, and a pressure reducing valve for decompressing the carrier gas discharged in a vaporized state from the gas cylinder to a predetermined pressure, and is constructed so that the pressure reducing valve and the spray gun are directly connected with a gas hose and mounted on a common truck. The sterilizing and disinfecting apparatus can operate with a simple structure requiring no power supply, and is much lighter in weight compared to conventional apparatuses.