This research developed a reliable and valid Japanese version of the Free Will and Determinism Plus Scale (FAD+) to measure people's belief in free will. Study 1 developed a Japanese version of the FAD+ using questionnaire data from 203 undergraduates. Study 2 tested the reliability and validity of the Japanese FAD+ in a sample of 362 adults. The results provide evidence that the translated scale has the same factor structure as the original scale. In addition, free will beliefs were associated with locus of control, sense of trust, and belief in a just world, indicating high validity of the scale.