The subjective evaluation of car interior noise is strongly related with the order spectrum profile of the car interior noise. In order to find the relation between the order spectrum profile of the car interior noise and its evaluation, the car interior noise recorded at the test course is modified its spectrum shape by applying the adaptive digital filters to increase and to decrease the order levels. After the modification of the original interior noise, the subjective evaluation of the test sounds was conducted to see the modification effect. As a result, the modification of the half order components relate to the increase and decrease of the pleasantness of the test sound. Together with this, concerning the spectrum envelope profile, the decay pattern to the high frequency side is the key point to improve the sound quality of car interior noise.