This research chose three kinds of sleeping bags with different fillings (A: interfill polyester, B: brushed polyester, C: down) and put them in two environmental conditions (Env. I : $25{pm}1^{circ}C$, $50{pm}10%$; Env. II : $18{pm}1^{circ}C$, $70{pm}10%$). The measured Skin temperature, Temperature and Humidity in sleeping bag, Rectal temperature and Psychological reaction. The results of experiment were as follows: 1. The mean skin temperature of Sleeping Bag B was the closest to the most comfortable value in the two environmental conditions. 2. Temperature and humidity in sleeping bags, in both environmental conditions, contained the value nearest to the most comfortable one in Sleeping Bag B. 3. Rectal temperature in both environments had a slight change in the range of antibody temperature in all the subjects of sleeping bags. 4. As subjective psychological reaction, both thermal and humid sensation approached the most comfortable zone in Sleeping Bag B.