The main purpose of this study is to analyze the effective body part to cool down the whole body under transient and nonuniform environment. A subjective test using car cabin was held to compare human responses. For the first hour, a car was placed in a chamber which created summer condition. Then two subjects were asked to ride in the vehicle, turn on the air conditioner, and vote their thermal sensation and comfort every 2 minutes. Their skin temperatures were measured during the test. As the result, the chest was the most effective body parts to cool. And there was a clear relationship between its skin temperature and thermal feelings. These data will be used as feedback to establish an index of such thermal environment.