Due to the development of civilization, the humans is privileged the rich of technologies for housing thermal environment. But, this kind of technological development caused enough trouble of energy excessive consumption. For solve this problem, many researchers strive to exploit the low energy sustainable techniques. For such a reason, the eco-friendly techniques of vernacular house are resurfacing. These traditional techniques are applied to a development of eco-friendly modern housing. They are no longer recognized as outdated products. On this context, this study proposes an scientific analysis on the thermal environment characteristics of Neolithic thatched-roof dugout hut(Um house). So far the several studies have been carried out in viewpoint of the history and structural compositions of the Um house which has been used as the normal housing for about 1000 years in the Neolithic era, however the thermal characteristics analysis of the Um house has never been studied. Um house is not a housing which has been composed by the scientific analysis or architectural design technology, but evolved empirically over a long period. This study on the thermal environment characteristics of Um house would provide basic information for the development of korean eco-friendly rural housing by korean climate characteristics. In this study, the thermal environmental characteristics of the Um house in the Neolithic era was analysed experimentally. The results of this study could be summarized as follows: 1. When the solar insolation and the ambient temperature in the daytime were $420W/m^2$ and $17^{circ}C$ respectively, the surface temperature of the Um house roof covered with the rice straw was $37^{circ}C$ and that in the roof $32^{circ}C$, and in the conditions above the air temperature in the room was $15^{circ}C$. 2. When the ambient relative humidity was 40%, that in the room of the Um house 50%, and at the ambient relative humidity of 90~100%, that in the room was 60%. 3. Through the experimental analysis, it was verified that the enthalpy and relative humidity is in an inverse relationship. 4. In general the comfort degree in the living space is changed with the seasonal climate, also in this study, the comfort degree in the room of the Um house in October and November was higher than that in May and June.