As people pays more attention to remodeling as a method to effectively improve, maintain, and manage building properties, it is important to ensure the economic feasibility of remodeling compared to reconstruction, instead of focusing on systematic regulations. In order to identify core technologies, the study set criteria to survey cost of a remodeling project by analyzing current status of remodeling projects. Based on the criteria, the study calculated average construction cost for two remodeling projects that were conducted recently, compared the cost with new construction projects, and examined major level works that are essential in a remodeling project. Based on the major level works, the study conducted interviews with construction experts to draw core technologies in design, structure and construction of a remodeling project.