This study induced characteristics of service environment and crowding perception in world fairs focusing on Yeosu World Expo and tried to identify visitors’ emotional responses to the service environment and crowding perception. Additionally, the effects of visitors’ attitude on controlling behaviors were verified using emotional responses as medium variable. The followings are the suggestions of the study. First, the right design matching with the theme of the fair, guidance and human services for visitors’ convenience and programs providing various things to see seemed to contribute much to the emotional responses of visitors. Organization Committee should do its best to improve the satisfaction of visitors by perceiving the importance of environmental perception elements in the Fair and making careful operation plan for service environments. Second, as exhibit is held in a limited space and a great number of visitors tend to visit in certain hours, it is difficult to avoid crowds. Thus, it is the best to avoid crowdedness but if it is not possible countermeasures to overcome such crowdedness should be made. Third, unpleasant feeling in the fair may give discomfort and inconvenience to visitors and they may feel like leaving the place as soon as possible. To maximize the stay of visitors, it is very important to manage and control the factors triggering negative feelings of visitors.