This study investigated relationships between self-identified cold tolerance with a questionnaire and thermoregulatory responses in cold environment, and personal morphological and life style characteristics. We conducted three experiments on 20 healthy males (21.9 yrs, 173.6 cm, 61.6 kg, 14.1% body fat). First, cluster analysis on a questionnaire survey was carried out to divide them into two self-identified cold tolerance groups. Second, we measured physiological responses in cold environment with acute cold exposure experiment. Third, BAT (brown adipose tissue) activity was evaluated by FDG (18F-fluorodeoxy glucose) –PET/CT method. As a result of cluster analysis, subjects were divided into the high self-identified cold tolerance group (n=9, 21.3 yrs, 174.2 cm, 64.7 kg, 14.1% body fat) and the low group (n=11, 22.3 yrs, 173.1 cm, 59.0 kg, 14.1% body fat). Skeletal muscle mass of the high group is significantly higher than that of the low group (P＜0.05). However, there was no significant difference in BAT activity. The high group tended to show higher thermogenesis at rest and maintained higher core temperature in cold exposure test. The low group had a tendency to adapt by behavioral thermogenesis because skin and core temperature decreased more in cold environment.