This study was conducted to investigate how PM10 concentration and Relative Humidity (RH) affected visibility in Jinju, Korea. A 9-yr dataset of 1 h averages for visibility, PM10, and RH data was analyzed to examine the correlation between these variables. On average, visibility decreased by 1.4 km for every 10 μg/㎥ increase in PM10 and by 2.1 km for every 10% increase in RH. In general, a negative correlation was observed between visibility and and PM10 concentration. However, under conditions of low PM10 concentration(< 15 μg/㎥) and visibility(< 2 km), there was a positive correlation between these two variables. In this case, RH levels were high (> 75%). A high correlation analysis between two variables need to be under control conditions with RH < 75%, PM10 15~100 μg/㎥, and visibility > 2 km.