Nowadays it has become increasingly popular to introduce new techniques for representing complex human behavior in determining the characteristics of pedestrian or car traffic. A typical technique is multi-agent simulation, developed in the frame of complexity studies. Meanwhile, in several larger cities, it has been common practice to redevelop urban functions in downtown areas in an innovative manner. If the downtown area is renewed, various visitors are attracted here causing numbers of pedestrians or car users to change rapidly and widely. Sometimes congestion is increasing in such a way that the commercial center is removed to a newly developed area. The objective of this study is to construct a behavioral model of visitors in downtown areas based on a multi-agent system. Specifically, a questionnaire survey is carried out among the people who visit the downtown area during holiday. The results are applied to construct basic rule-based behavior of an agent. The rules are focused on the relation between the visitor's behavior and the environment. Each agent acts on the map including geographical information. In addition, the change of pedestrian behavior corresponding to the spatial environment changes is also examined by use of specific data on them. Moreover, an actual behavior survey was executed simultaneously. As a result, it was found that the estimated behavior by simulation corresponded with the actual case. Using this simulation model, some scenario analyses could be examined. The future situation after redevelopment in the downtown area can be simulated on the basis of the state before the redevelopment. Finally, the possibility of application of multi-agent simulation models was provided for various types of human behavior, such as the estimation of evacuation following an earthquake disaster, the estimation of commuters' activities in rush hour and so on. JEL Classification: C15, R11