The present study was to investigate whether increasing thermal insulation affects thermal sensation in the hands and feet; and whether aging is an influential factor in the relationship between thermal responses and subjective thermal perceptions. Six young males (YM), 5 young females (YF), 6 elderly males (OM), and 6 elderly females (OF) volunteered as subjects. Subjects conducted two trials at a constant air temperature of 19°C: One condition included thermal underwear (19CUW) while the other did not (19C). The results showed that (1) rectal temperature (T_re) did not show any significant differences between conditions with and without thermal underwear. The T_re of the OF was greater than that of the YF ( p <0.05) for the 19C condition, while the young and elderly male groups showed similar values. (2) The hand and foot skin temperatures (T_hand, T_foot) were greater in the OF than in the YF group for the 19C condition ( p <0.001). (3) For overall thermal sensation, the OF group was less sensitive to differences between the 19CUW and 19C condition, when compared with the old male and young groups. (4) For thermal sensation in the hands and feet, the elderly groups were less sensitive than the YF. In particular, all elderly females felt the hands were thermally neutral, even in the 19C condition. (5) Hand thermal sensation for the OF group appeared to be irrelevant to T_hand. (6) Thermal preference of the elderly groups did not change significantly after adding thermal underwear compared to the young group. In conclusion, wearing thermal underwear in mild cold did not affect local skin temperatures and thermal sensation in the hands and feet for the elderly male and female groups. Adding thermal underwear in mild cold affected the hand skin temperature and thermal sensation of the young female group. In particular, elderly females had specific features concerning local skin temperatures and thermal sensations distinguished from elderly males and young groups.