The treatment of styrene vapor was carried out using the biofilter packed with loess/polyurethane composite during continuous operation of 74 days. The microorganisms were adapted within 2-3 days under the experimental conditions of inlet concentration and empty bed contact time (EBCT). At 200 sec of EBCT, the removal efficiency of styrene was 100% with 200 ppmv of inlet concentration, while 92% with 400 ppmv of inlet concentration. The biofilter showed the stable removal efficiencies of over 74 % under the EBCT range from 300 to 75 sec at the 150 ppmv of inlet styrene concentration. The maximum capacity of styrene removal for the biofilter packed with loess/polyurethane was 29 g/m3/hr. During continuous operation of 74 days, pH of the drain water changed slightly and the pressure drop through the biofilter column was below 45 mmH2O/m.