The purpose of this study is to evaluate the thermal comfort in a classroom of college. A field study conducted in the classroom where about 40 college students aged 18-19 years took a class and was not air conditioned in summer. The thermal environmental factors in the classroom and thermal sensation and comfort by the students were measured from May 2000 to May 2001. The classroom temperature were higher than that of school environmental sanitation guidelines both in summer and winter. Most of the students felt too hot and uncomfortable in summer. When the classroom has SET* of over about 28 degrees Celsius, most of the students may feel hot and uncomfortable. When the classroom has SET* of about 26 degrees Celsius, most of the students may feel thermal comfort.