This study deals with the operational effectiveness of roundabout. The roundabout is currently under consideration in our country depending on the result of existing researches, that the roundabout decreases delay and is environmentally friendly compared to the signalized intersection. The purpose of the study is to analyze the operational effectiveness of the roundabout by the change of pedestrian traffic volume. In pursing the above, this study gave particular emphasis to designing a network of roundabout, developing some scenarios for analysis including both entering traffic volume and pedestrians volume, and comparatively analyzing the average controlled delay time per vehicle. In this study, VISSIM model was used as a tool for traffic simulation. The main results are as follows. First, as a result of analyzing a traffic delay based on the pedestrian traffic volume, pedestrian traffic volume was analyzed to have a great impact on the roundabout operation. Second, the more pedestrian traffic volume were evaluated to indicate the more traffic delay. When the entering volumes with 1,000persons/hour (pedestrian volume) were more than 800pcph in the single-lane and 1,600pcph in the double-lane roundabout, the operational efficiencies of signalized intersections were evaluated to be better than those of roundabouts.