The development of an equitable city has been the primary goal of recent urban planning. Whereas previous urban planning has addressed problems caused by urbanization and population growth, current urban planning must closely consider demographic changes such as an aging society. An aging population, characterized by an increased need for regular healthcare and a growing reliance on public transport, can pose a major challenge to equitable cities. Thus, it is necessary to scrutinize the medical and public transportation links in urban planning strategies to create a more equitable city in an aging society. This study analyzed primary care accessibility for older adults using public transportation in Seoul and considered whether it is socially and economically equitable. Primary care accessibility was derived using the modified 2SFCA model and the Seoul Public Transportation API and social equity was analyzed using the concentration index and concentration curve. The results showed that primary care accessibility of the elderly is related to public transportation mobility, medical facilities and the distribution of elderly populations, revealing both social and economic inequality. This analysis suggests the need for integrated urban planning for an equitable city in an aging society, with implications for efficient resource distribution.