The invention provides a method of screening a therapeutic agent for allergic airway inflammation and/or airway hypersensitivity, comprising using an IL-17RB positive NKT cell, as well as a therapeutic agent for allergic airway inflammation and/or airway hypersensitivity, containing a substance capable of inhibiting or eliminating the Th2 cell-like function of an IL-17RB positive NKT cell as an active ingredient.