A method of evaluating the sensitivity grade of an interior material used in vehicles comprises: evaluating sensitivity properties of an interior material before providing noise factors; evaluating sensitivity properties of the interior material after providing noise factors; averaging each of the sensitivity properties evaluated before the provision of noise factors and after the provision of noise factors to obtain the average value (safety factor) of each of the sensitivity properties; comparing the average value of each of the sensitivity properties with a preset target value of each of the sensitivity properties to compute a target value achievement level of each of the sensitivity properties; and determining the sensitivity grade of the interior material based on the sensitivity property with the lowest target value achievement level. By providing an objective standard to evaluate sensitivity properties of an interior material used in vehicles, the present method(s) eliminates the difficulty in communication between customers and manufactures and quality control regarding the sensitivity grade of interior materials used in vehicles.