OBJECTIVE: In Japan, a recent opinion poll in 2017 showed that 41.9% of the respondents wished to donate their organs but only 12.7% declared their intention to donate or to not do so. Therefore, it is important to explore measures to prompt more individuals to register their intention about organ donation. METHODS: A field experimental questionnaire survey was conducted to confirm the effect of a prompt message for registering intentions for organ donation, which was communicated at a driver's license center. The study employed a prospective randomized control design. 7615 individuals visited the Tokyo Fuchu License Examination Center to update their driver's license and received leaflets including a message prompting organ donation registration and the questionnaire. Of the participants who received leaflets, 3224 respondents provided complete responses to the questionnaire (valid response rate: 42.3%). Subsequently, a questionnaire survey was conducted to assess the participants' willingness to register for organ donation. A control condition and the following types of messages were used: "Peer-framed," "Gain-framed," "Loss-framed," "Reciprocity-framed," and "Peer + Reciprocity-framed." RESULTS: The reciprocity message emerged as a significant predictor of increase in immediate decision response. The loss-framed message was a significant predictor of decrease in no intention to register. CONCLUSIONS: This study found that reciprocity and loss-framed messages promoted the readiness to register for organ donation among individuals from a Japanese urban area. Mandatory distribution of prompt messages at the every driver's license centers in Japan would be recommended.