Atopic dermatitis (AD) is a chronic inflammatory skin disease, with its major clinical feature being persistent itch sensation in the skin. There are extremely few animal models to reproduce the complicated condition of a patient with AD; therefore researchers have been confronted with some difficulties in pathologic analysis and drug development for AD. Although various models have been proposed and developed, there is no doubt that the spontaneous mouse model, NC mice, gave the greatest impact. NC mice enabled us to analyze pathogenesis of allergic skin abnormalities as well as development of new drugs for AD. However, many questions still remain in the pathogenesis of AD. In recent years, the study of the itch has attracted our attention because itch is one of the most unbearable symptoms of AD. For development of an effective treatment to overcome the itch, not only a precise animal model but also an accurate evaluation protocol are needed. This review summarizes some mouse models of AD, particularly focusing on NC mice, together with a novel evaluation system for scratching behavior of mice to help the understanding of researchers.