In order to identify the factors influencing the comfort in the passenger room of train, we polled about 1,500 travelers by circulating questionnaires and took some physical indices such as vibration, noise, temperature, CO₂ concentration and pressure change in the commercial trains. The results are summarized. Correlation coefficient between composite values in the any combination of the measured physical indices and passengers' overall comfort rating doesn't exceed 0.4. On the other hand, if the subjective evaluation for each physical index is added to the composite value, correlation coefficient surpasses 0.7. Factors which determine the overall comfort rating are vibration, noise, area of seat surface, design of passenger room and cleanness of air.