A temperature adjustment method comprising: forming a wet surface wet with a cooling medium by supplying the cooling medium to a rear surface of a temperature adjustment surface of a component member in a processing chamber of a substrate processing device comprising the processing chamber which performs predetermined processing on a substrate and is vacuum-exhaustible; and adjusting a temperature of the temperature adjustment surface due to latent heat of evaporation of the cooling medium by evaporating the cooling medium which forms the wet surface by adjusting a pressure in an evaporation chamber which isolates the wet surface from an atmosphere around the wet surface.