PROBLEM TO BE SOLVED: To provide a method of cleaning an air shower room and an air shower device capable of efficiently sterilizing microorganisms.SOLUTION: In the method of cleaning the air shower room, a sterilizing gas is set into the air shower room 10 while stopping the distribution of pressurized air when a person or a substance enters the air shower room 10, and then the pressurized air is sent. Furthermore, after the pressurized air is sent, the air is sent to the air show room 10 from a ceiling side to a floor surface side of the air show room 10 together with the sterilizing gas.