As cities strive to address environmental issues and contribute to the Sustainable Development Goals, the transportation sector has been a key focus for efforts. In particular, the adoption of electric vehicles (EVs) has been identified as a crucial solution to mitigate air pollution and reduce greenhouse gas emissions. However, EVs are not competitive with internal combustion engine vehicles due to their high price and lack of charging infrastructure, and EV subsidies are being provided to address this. Because EV subsidy effects depend not only on the characteristics of the individual consumers but also on the future technology maturity of the EV and the level of infrastructure deployment, they should be analyzed in an integrated manner. In this study, we analyze the subsidy effect by conducting a stated preference survey and constructing a logit model assuming the vehicle purchase situation of EVs and internal combustion engine vehicles (ICVs). Since the future technical maturity of EVs and the establishment of charging infrastructure are uncertain, we mitigated this through scenario analysis. Our results show the air pollution reduction effects of EV subsidy policies and provide insights for policymakers that EV subsidy policies cannot achieve sufficient effects if they are implemented unilaterally without technological maturity or infrastructure construction.