PURPOSES : In this study, the social cost of on-street parking spaces was estimated by dividing it into private and external costs. METHODS : We established a methodology and conducted a case analysis of Seoul. Private costs were estimated from the guidelines and historical data collected. The opportunity cost of the land was estimated using spatial information. External costs built a macroscopic model (using TransCAD) and estimated travel time, operation, accident, and environmental costs. RESULTS : The social cost per space was estimated at 77 million won. Private costs were analyzed as 133.3 billion won, the opportunity cost of the land was 68,555 billion won, and external costs were 118,25 billion won in 2020. CONCLUSIONS : In this study, a methodology for estimating the social cost of a road parking facility was established and applied to the case of Seoul. Therefore, it is expected to contribute to the objective reviewing of the feasibility of policy evaluation or facility investment related to parking facilities.