In addition to measurement by on-board emission measurement system, analysis by a traffic flow simulator is one of the most effective ways to identify pollution locations on actual roads. In this study, the real-world emission behavior of a direct-injection gasoline vehicle was analyzed and a emission prediction model for a traffic flow simulator was constructed based on this analysis. The result of the emission prediction using vehicle speed, acceleration, and road gradient showed that the CO2 prediction was accurate, but the NOx prediction needed to consider the fuel cut timing to improve prediction accuracy.