This study aims to clarify effects of various environmental grades on thermal comfort. Field surveys were conducted in five semi-outdoor spaces in Tokyo, consisting of thermal environment measurement, questionnaires about thermal comfort and impression of surveyed spaces and real-time sensation voting. By impression evaluation and comparison of the regression curves of standard new effective temperature (SET*) against percentage of “uncomfortably warm”, the surveyed spaces were classified into two categories: “outdoor tendency” and “indoor tendency”. By regression analysis of real-time sensation voting result using hierarchical Bayesian approach, environmental grade was clarified to affect the correlation between pleasantness/unpleasantness and air velocity.