To provide a hot air temperature controlling method that can increase a temperature at high speed without causing overshoot.

The hot air temperature controlling method includes, in a process of blowing hot air heated at a hot air generating section 20 for heating of hot air and air volume control blow through a hot air duct 40 from a hot air blow-off section 30, measuring a temperature of the hot air generating section 20 and a temperature of the hot air at the hot air blow-off section 30, controlling the temperature of the hot air generating section 20 based on these temperatures, and controlling the temperature of the hot air at the hot air blow-off section 30 to a desired value.