This study examines the effectiveness of economic incentives in promoting electricity-conservation behavior among Japanese households. Fifty-three Japanese households participated in a field experiment and were offered monetary rewards depending on their rate of reduction in electricity consumption. To avoid bias in sample selection, which is typically present in previous studies, we adopted a request-based approach for recruiting participants. Results showed that only 34% of the participants succeeded in reducing their electricity consumption, and the average reduction rate was –4.8%. Econometric analysis confirmed that monetary rewards had a positive influence on the electricity conservation behavior, especially of family members who typically stay at home on weekdays. Responses to the questionnaires administered before and after the experiment suggest that participants may have underestimated the marginal costs of the electricity conservation behavior. The efficacy of economic incentives, established in our study, offers a potential measure for encouraging electricity-conservation behavior among Japanese households.