A virtual environment system for human behavior analysis, called a service field simulator, and its application to marketing investigation are described. The practicability and advantages of applying this service field simulator to marketing investigation are demonstrated through two case studies involving actual business scenarios. The first case study highlights the similarities and differences that occur when in-store marketing investigation is carried out in a real store versus a virtual store. The results of the second case study, an actual in-virtual-store marketing investigation, verify the feasibility of the proposed service field simulator.