Emission of air pollutants such as nitrogen oxides ($NO_x$), hydrocarbons (HC), $SO_2$, and particulate matter (PM) and $CO_2$ from ship during 2009 in Busan port was estimated based on activity-based method. The significant fraction (> 50%) of ship emission resulted from container and general cargo ships. Emission at port operation mode was the most dominant compared to at sea and maneuvering modes. Emission at North port was the largest source of air pollutants among ports. The magnitudes of air pollutants $NO_x$, $SO_2$, HC, $CO_2$, and PM in Busan port were $8.7{ imes}10^3$, $8.23{ imes}10^3$, $0.35{ imes}10^3$, $4.86{ imes}10^6$, and $0.67{ imes}10^3$ ton/yr, respectively. The ratio of $NO_x$ to VOC is about 25. Our ship emission estimate is 2 times higher than that in CAPSS emission inventory.