Frontage space of building is a kind of privately owned pubic space, which has been created in a city to, among other things, provide usable pedestrian space by the setback requirement under land use laws, such as Building Code and the National Land Planning and Utilization Act. But, it has been also frequently criticized that they are mostly used for private purpose. This study explores the legal limitations of the frontage space of building and proposes the improvement schemes. In doing so, it examines the constitutional requirements and legal theories regarding land use control and draws the legal aspects of the space. In conclusion, it finds that frontage space of building may constitute a regulatory taking under the Korean law if it severly restricts private use of the space. Therefore, it suggests an approach based on the incentive system to acquire the space, and proposes to establish an effective guideline to manage the space. It is expected for this study to lay a legal foundation in designing and managing a frontage space of building.