The objective of the study is to investigate the distribution patterns of airborne bacteria and fungi in the feedstuff manufacture factory. The mean levels of airborne bacteria and fungi in the feedstuff manufacture factory were 113(±18) cfu/㎥ and 89(±5) cfu/㎥ for pelleting process and 198(±5) cfu/㎥ and 124(±12) cfu/㎥ for powdering process, respectively. The percentage of respirable and total concentration of airborne bacteria and fungi in the feedstuff manufacture factory ranged from 60% to 90% and were higher in pelleting process than powdering process. The ratio of indoor and outdoor airborne microorganism exceeded 1.0 regardless of types of feedstuff manufacture process. Based on the result of the study, there would be an association between environmental factors such as relative humidity and carbon dioxide and airborne microorganism`s bioactivity.