It is necessary for every organization in Japan to address the risks of natural disasters, Japan being a high-risk area. Recently, local governments have been required to maintain not only the level of administrative services, but also the level of medical services that is required if a disaster occurs. However, no previous studies have clarified what countermeasures for maintaining the level of medical services should be taken by a local government. This study identifies important concepts, such as “medical needs required when a disaster occurs,” “medical service delivery capabilities to correspond to medical needs,” and “the gap between needs and delivery.” The purpose of the countermeasures is to eliminate the gap between needs and delivery. From these concepts, we derive five types of countermeasures. For example, Type 4 means that it is necessary to obtain the additional medical resources from other organizations in the area or other areas to improve medical services’ delivery capability. Moreover, 15 more detailed countermeasures are clarified by taking into account the medical features of the organization. Finally, we verify the effectiveness of the proposed countermeasure types in a hospital setting.