Since the comfort feeling and satisfaction of a toilet seat is important for the defecation, we investigated the design parameters and affective attributes for toilet seats, and developed the affective model that explains the level of customer satisfaction. To achieve, objective measurements of design parameters and total 19 number of relevant affective attributes including appropriateness of each design parameter were collected from literature review and user interview. Then, a subjective experiment was conducted on five different toilet seat samples. As a result, 6 factors of surface and fatigue, appropriateness of toilet size, accessibility, immaculateness, centroid, and physical tensity were revealed by factor analysis. An affective model for seat comfort was also developed by regression analysis, and the relationships between each factor and design parameters were investigated through correlation analysis. This study is expected to contribute in improvement of toilet seat comfort as a preliminary study.