The concentration of air pollutants such as NOx and SPM is significantly increased by automobile exhaust gas in enclosed spaces frequented by automobiles. An investigation into air pollution at a bus terminal underneath a modern building was carried out. Average concentrations of NO2, NO and SPM were 63ppb, 162ppb and 188μg/m3 respectively, and maximum concentrations of NO2, NO and SPM were 137ppb, 712ppb and 1045μg/m3 respectively. The contribution of dust sources was estimated using the concentration of EC (Elemental carbon), OC (Organic carbon) and Fe. The contribution of smoking in the waiting room was 44.6%, while the contribution of diesel smoke in the outdoor waiting room was 41.1%. A roadside-type air cleaner was set up in the waiting room at the bus terminal. The removal efficiency of NO2 by the air cleaner was 50-60%.