Even in modern times, we are accustomed to the lifestyle of floor heating system in which the floor is heated for warmth like Ondol, which is the traditional Korean heating system. So, this study was designed to understand the preferred floor temperature through the questionnaires targeting the local residents living in K region. This study would also find out the floor temperature which is preferred by young people and old people through the experiments. The findings are as follows; (1) the old people do not prefer the temperature higher than young people do. It was found that the old people prefer the floor temperature of 40℃ under the air temperature of 20℃ or the floor temperature of 41℃ under the air temperature of 20℃. (2) Both young people and old people tend to like the average skin temperature of 35.5℃. The skin temperature which both young and old people like was 35.2℃ under the air temperature of 24℃ and the skin temperature preferred by young people was 0.4℃ higher than that preferred by under the air temperature of 20℃ (p<0.01). (3) It was found in the questionnaires that the young people prefer the higher floor temperature in terms of age and that the people who get older in their 50s or higher tend to prefer the lower temperature.