To measure economic effects of changes in environmental quality caused by climate change in Japan, we estimate beach loss damage costs in Japan and in each prefecture and evaluate the economic effectiveness of hypothetical adaptation measures to restore sandy beaches. For analyses, we use a computable general equilibrium model (CGE) that integrates a utility function with environmental quality factors as an independent variable derived from a recreation demand function in a travel cost method (TCM). We use future projections of beach loss rates in 2081–2100 based on ensemble-mean regional sea-level rise (SLR) for four Representative Concentration Pathway (RCPs) scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). The main findings of our study are presented as follows. (1) In 2081–2100, beach loss damage costs were estimated respectively as 398.54 million USD per year for RCP2.6, 468.96 (m.USD/year) for RCP4.5, 494.09 (m.USD/year) for RCP6.0, and 654.63 (m.USD/year) for RCP8.5. (2) For all RCPs, six prefectures for which the cost–benefit ratio exceeds 1.0 were Kanagawa, Osaka, Hyogo, Hiroshima, Saga, and Kumamoto. Our hypothetical adaptation measure of an artificial beach enhancement is expected to be quite effective as a public works project in these prefectures.