This research examined the validity of whether the PMV index-based comfort- or uncomfort-indoor environments could be classified by the facial skin temperature, one of the physiological indicator for human. To do this, we distinguished between a comfort thermal environment and an uncomfort thermal environment using the PMV value, and then facial skin temperatures were measured in both environments. As a result, the facial skin temperature of occupants were different between the comfort- and uncomfort-indoor environments. It suggested that the facial skin temperature could be used in shaping the comfortable indoor environment based on the PMV index. While this result suggested the PMV index-based on comfort and uncomfort indoor environments could not be valid, because the facial skin temperature was lower in the uncomfort thermal environment than in the comfort thermal environment.