The actual thermal environment and bedclimate on Ondol were investigated by the regions and housing styles in each season. The subject were sixty healthy men and women, 30 of them live in apartment, and 30 of them live in detached house. 20 of them live in Wonju, 20 of them live in Cheongju and 20 of them live in Pusan. The results are as follows: 1) The subject slept in this conditions; 23.1$pm$2.4$^{circ}C$ and 38$pm$8.8% RH in spring, 27.1$pm$1.5$^{circ}C$ and 68$pm$6.4% RH in summer, 27.1$pm$1.7$^{circ}C$ and 47$pm$11.1% RH in autumm, and 24.9$pm$3.3$^{circ}C$ and 41$pm$10.7% R.H in winter The temperatures of the floors were 38.6$pm$5.$0^{circ}C$ in the spring, 26.7$pm$1.9$^{circ}C$ in the summer, 29.4$pm$4.7$^{circ}C$ in the autumm, and 30.0$pm$5.8$^{circ}C$ in the winter. 2) Each thickness of the quilts was thinner in the summer than in any other season, but the differences in the thickness of each mattress was not significant by the seasons. 3) The differences of the bedclimate and the clothing microclimate were significant by the regions and housing in each seasons. The inside of temperature and humidity of sleepwrar were highest in summer. The bedclimate showed high correlation with the clothing microclimate. 4) The differences in the sensation which the subjects felt about temperature and comfort of the bedroom conditions were not significant by the seasons, regions, or housing styles. But the subjects felt more humid in the summer and spring than in the autumm and winter.