The collapse of non-earthquake-proof houses during severe seismic events results in casualties and hampers firefighting efforts, underscoring the imperative of formulating policies to enhance the earthquake resilience of rental properties. This study proposes a method to estimate the required financial support for improvements and compares the efficacy of tax incentives versus subsidies for promoting earthquake-proof conversions of rental housing for the first time. Combining the contingent valuation method and the discounted cash flow method, the study develops a model to examine consumers’ evaluation of earthquake-proof conversions of rental houses and determines a rental firm’s profits following such conversions. Application of these methods to analyze rental apartments in Tokyo and Miyagi Prefecture reveals that tenants are willing to pay less than 3000 yen/month in addition to their present rents for earthquake-proofing measures. This amount falls short of ensuring profitability for rental firms, emphasizing the necessity of financial support to bolster earthquake resilience in rental housing in Japan. Drawing from this analysis, the study proposes a method to determine the requisite financial support for earthquake-proof conversions, evaluating the merits of municipal fixed property tax reduction versus subsidy provision. The findings offer valuable insights for policymakers, informing strategies to incentive earthquake-proof conversions and enhance disaster preparedness in housing sector.