Railway stations had been considered to be the transient space hitherto, but they started to have larger commercial spaces lately. Not only small shops but also big shopping malls are introduced. Therefore the usage of stations is changing for the passenger to stay longer and environmental quality in stations is getting more important. However, it is unfavorable to install air conditioning systems because concourses are semi-outdoors. Thermal comfort in stations was found to be unsatisfactory for the passengers especially in summer according to the field survey conducted in 2004-2006. Thermal environment exceeding 32 ºC in SET*(standard effective temperature) was recorded often in summer, an upper limit where more than 20% of passengers voted the thermal environment to be unacceptable. Mitigating the thermal environment by passive design would become possible by aiming 32 ºC SET* as the target. Besides, as low air velocity and high solar radiation are considered to be the main factors of discomfort, the solutions to these factors need to be examined for comfortable stations.