BACKGROUND: The Childhood Atopic Dermatitis Impact Scale (CADIS) was developed to measure the impact of AD on QoL in both affected children and their families. However, no scale of this kind exists in Japan. The aims of this study were to validate the Japanese Culturally Modified Version of the CADIS (JCMV-CADIS) and to describe the family impact of children with AD in a Japanese context. METHODS: Participants included primary-caregivers for children with AD between 2 and 6 years of age. Interviews were conducted, and new items for the Japanese version were drafted. Reliability and validity were evaluated and compared with the original CADIS, and unique features of the Japanese version were analyzed. RESULTS: Exploratory factor analysis revealed the following factors: "Symptoms" and "Activity Limitations and Behavior" in the Child domain, and "Emotions Related to Social Factors," "Emotions Related to the Child's Condition," "Family and Social Function," "Complexity of Care," and "Approaches to Management of AD in Daily Life" in the Parent domain. The latter two factors were unique to the JCMV-CADIS and were not derived from the Original. "Emotion" was split into two independent factors. All factors showed good reliability (internal consistency and stability) and validity (concurrent validity and discriminant validity), except for the concurrent validity of "Approaches to Management of AD in Daily Life." This factor seemed to reflect characteristics similar to the family-related function. CONCLUSIONS: The JCMV-CADIS is a QoL scale developed for Japanese children with AD and their families. Further evaluation of clinical applicability is needed.