The concentration of fine dust rises during Asian dust event. In order to establish an effective countermeasure against a high concentration of fine particles, it is important to characterize the particle size distribution and grasp the particle diameter which has higher concentration than the other. The particle diameter which occupied the highest portion during Asian dust events was about 4.5 μm. Particle with 2.5 μm and 5.0 μm also accounted for relatively higher percentages than the other. The proportion of PM2.5 out of PM10 was 46% in the absence of Asian dust which decreased rapidly to 24% during the events. Particle diameter with 4.5 μm indicated the highest mass concentration in the presence of Asian dust and 3.3 μm showed the greatest increase in concentration which increased 3.9-fold against 2.4-fold that of PM10. When PM10 concentration increased during the event, coarse particles with diameter from 2.8 μm to 5.7 μm demonstrated the highest concentration. Timedependent concentration in a residential area on normal day indicated that ultra-fine particle had relatively higher concentration in the morning, but coarse particle in the afternoon.