Aim: This study aimed to develop an Attitude Scale on Radiation Emergency Medicine (ASREM) for Japanese nurses and to evaluate its reliability and validity. Methods: The original ASREM was developed based on interview data and a comprehensive review of the literature. A revised 35-item version was developed by examining the content validity of the original scale. Subsequently, we investigated the reliability and validity of the scale in 798 nurses employed at 31 primary, secondary, and tertiary medical institutions providing radiation treatment in Japan. Results: Valid responses were received from 376 nurses. After selecting items based on response bias, we conducted exploratory factor analysis using principal factor analysis with promax rotation. The following four factors comprising 25 items were finally extracted: 14 items, "confidence in knowledge and skills"; 6 items, "psychological resistance"; 3 items, "responsibility as a medical professional"; and 2 items "interest in radiation emergency medicine." The reliability of the scale was confirmed by a Cronbach's alpha internal consistency reliability coefficient of 0.93 (0.69–0.72 for subscales; the correlation coefficient for the fourth factor was 0.52). Criterion-related validity was confirmed by intervention using the resistance score related to nurses' fears of contamination from patients with radiation exposure. Construct validity was confirmed using consent to participate in the radiation exposure medical care team. Confirmatory factor analysis was conducted, and a hypothesized statistical model was found to fit the actual data. Conclusion: The present ASREM was determined to be appropriate for Japanese nurses and to have satisfactory reliability and validity.