The most pivotal approach to improve subway indoor air quality (IAQ) is to examine the emission sources and particulate behavior. Therefore, the main objective of this study is to investigate the particulate behavior in the subway. In order to examine IAQ in the subway, a sampling and measurement campaign was carried out for 35 sites during the summer and winter seasons from May, 2005 to February, 2006. In case of 24 hour measurement, the mean concentrations ($PM_{10}$-24 hr) of platform and waiting room were $156.18{pm}53.79{mu}g/m^3$ and $111.00{pm}53.31{mu}g/ m^3$. Besides, as a result of 20 hour measurement, the mean concentrations ($PM_{10}$-20 hr) of platform and waiting room were $146.09{pm}53.71{mu}g/m^3$ and $99.08{pm}42.77{mu}g/m^3$, respectively. In general, $PM_{10}$-24 hr was higher than $PM_{10}$-20 hr, and both PM concentrations showed a high correlation coefficient (r=0.803). It was found that the $PM_{2.5}$ concentration ($l09.56{pm}28.24{mu}g/m^3$) in winter was higher than that ($83.66{pm}57.82{mu}g/m^3$) in summer.