Recently, there has been growing public concern over IAQ(lndoor Air Quality) of automotive cabin. Because air inside an automotive cabin is exposed to various pollution substances, it could be a serious threat to passengers" health and safety. While there are many suggestions to improve IAQ, we analyzed factors including CO<SUB>2</SUB> exhalation from human model and various operating characteristics of HVAC system(flow rate, fresh air to recirculated air) to understand the effects on the IAQ. Also, for the active control of automotive IAQ, we proposed a optimal HVAC operating condition and locations of CO<SUB>2</SUB> sensors.