Introduction: The development of cultural sensitivity is essential for health care professionals but there are few tools to measure this quality in Japan. The purpose of this study was to develop a scale of cultural sensitivity for Japanese health care professionals and examine its reliability and validity. Method: A draft scale was created through conceptual analysis and a questionnaire was completed by 515 health care professionals and 1,322 college students. Exploratory and confirmatory factor analyses were used to determine suitable scale items and examine model fitness. Results: The four-factor 18-item scale showed acceptable model fitness. Cronbach’s α coefficient exceeded .90 and correlation coefficients for criterion-related validity were over .29. Construct validity was confirmed by the significantly higher score of the cross-culturally experienced groups. The intraclass correlation coefficient was .642 (professionals) and .722 (students). Discussion: This reliable and valid scale for Japanese health professionals and college students may be used to evaluate training programs to increase their cultural sensitivity.