The purpose of this study was to review physiological responses and subjective sensations in the cold environment when the subjects wore ensemble with different clo values. Seven healthy male subjects participated in this experiment. This experiment was conducted in a climatic chamber with $-10^sC$ and 50%RH. Subjects wore five different kinds of ensemble[C1 (4.453 clo), C2 (3.452 clo), C3 (2.865 clo), C4 (2.387 clo), and C5 (2.280 clo)]. The experiment was composed of 20 min of rest period, 20min of treadmill exercise(6 km/h) period, 30 min of recovery period. We monitored skin temperature on 7 sites, clothing microclimate and subjective sensations. The clo value had positive correlations with mean skin temperature and clothing microclimate. The subjects feel more warm and humid as the clo value goes up. The subjects reported comfort when they wore C1 and C2 ensemble having over 3 clo value. However, they felt less comfortable during the exercise period since there was high humidity. Skin temperature on the extremities were more dramatically changed by the exercise rather than clo value. Thus it seems that in the cold environment, heat balance can mostly be controlled by the choice of clothing, and the clothes with high clo values can provide higher insulation. In conclusion, our findings suggest that it would be more effective to control clo value depending on the activity level for maintaining comfort level in the cold environment.