Insomnia is common disease generating about 30% incidence in Korea. It describes not only a state of a lack of sleep but also a causative factor for both psychological and physical disorders. According to Oriental Medicine theory, there are many causes of insomnia, and Wibulhwa(胃不和) is one of causes. In this study, we diagnosed as Wibulhwa(胃不和) for three patients and mainly treated with Modified Yukgunja-tang. We compared with before and after Insomnia Severity Index(ISI) treatment. As a result, ISI score falled, and it showed an improvement in insomnia. So we suggest that Modified Yukgunja-tang might be usefully applied to the treatment of insomnia caused by Wibulhwa(胃不和).