Previous religiousness scales have been developed in Christian contexts; we developed in Japan, where diverse religions coexist, the Scale of Motives for Faith comprising novel dimensions to facilitate intercultural comparison studies between Western and Eastern religions including monotheistic, polytheistic, and atheistic ones. In Phase 1, items were extracted using an adapted Delphi method; in Phase 2, validity and reliability were tested in a nationwide survey. In Phase 1, twenty experts representing Buddhism, Christianity, Shinto, Islam, and new religions extracted 16 items; in Phase 2 using a pilot scale, 1093 respondents’ beliefs were analyzed. After one item was excluded, confirmatory factor analysis evaluating the 15-item-5-factor model indicated acceptable goodness of fit. In hypothesis testing, 78% were accepted. Cronbach’s alpha ranged 0.79–0.93 and the intraclass correlation coefficient ranged 0.50–0.65. The Scale of Motives for Faith may serve to compare motives for religious faith worldwide and to identify motives for faith in relation to social, psychological, and health impacts across countries, religions, and cultures.