Currently, public rental housing is biased toward quantitative supply of housing, and many factors that do not takeinto account the situation of tenants are emerging as social problems. The international community aims to achieve carbon neutrality to cope with global warming and climate change, and the need for eco-friendly materials and recycling methods is emerging in the construction field to reduce greenhouse gas emissions. This study proposes customized remodeling of public rental housing using a modular method that can improve and revitalize the living environment of public rental housing and provide smooth rental housing. First of all, customized public rental housing is a customized method that partially applies and remodels residential spaces, public spaces, and convenience facilities that reflect the needs of residents, unlike the existing remodeling method that is re-constructed after full demolition. In addition, the modular method is a type of de-site construction work, and it is possible to maximize air shortening and reuse the module by pre-manufacturing and transporting unit modules to the site in a factory. Therefore, the urban housing problem, which is emerging as housing poverty for small households,requires a differentiated public rental housing supply method to cope with social changes such as lack of new housing, COVID-19, enforcement of the Severe Disaster Penalty Act, and carbon reduction through FM. Second, if residential performance is improved and expanded by remodeling existing public rental housing, it is possible to improve the settlement environment and supply low-cost and high-efficiency rental housing. Third, by using the modular method, it is possible to develop a house tailored to consumers and compliant with social changes. It is proposed as a method that can quickly improve the residential environment and supply housing for public rental housing by constructing customized remodeling that reflects the aforementioned demand of residents.