This study is to present a methodology for estimating influential spheres and setting its direction influential urban spatial structure due to the implementation of one-way system. It is practically necessary to consider the influential spheres and current state of land use such as use of buildings within the influential spheres in implementing one-way system. In this respect, this study 1) presented a methodology for estimating influential spheres of one-way system and developed application to automate it. 2) It also presented the indicator of ‘reachability / accessibility’ that are suitable for the use of building within the influential spheres as well as methodology for setting direction of one-way system using this. Downtown areas of Seoul and Yongin, which have different conditions of urban spatial structure, were selected as the analysis target areas for study to prove the effectiveness and validity of methodology presented in this study. As a result of the analysis of influential spheres, the effectiveness of the methodology presented in this study was confirmed. In addition, issues that are difficult to predict without using methodology presented in this study were found. These findings can be summarized as follows. 1) When setting the direction of one-way system differently, the locations of affected areas and beneficiary areas are also different. 2) Affected areas and beneficiary areas are not clustered and can be dispersed. 3) The scope of influential spheres that includes both affected areas and beneficiary areas is almost the same in its scope and scale regardless of the type of one-way system. 4) The influential spheres doesn’t form a circle around the road with one-way system. Next, The result of analysing one-way system direction using the indicator of ‘reachability / accessibility’ that are suitable for the use of building within the influential spheres confirmed the validity and effectiveness since it had the same direction with one-way system in operation currently. Therefore, methodology for estimating influential spheres of one-way system and setting their direction presented in this study is expected to be used as basic data when designating and reorganizing one-way system for roads in the future.