Cooperation with local communities is essential in the Japans System of Natural Park (Zoning-System), but insufficient interest in such systems is often cited as a problem. Through the promotion of inbound tourism in recent years, health tourism has been growing from the aspect of the development of local communities. This study clarified medical institutions’ interest in natural parks. A national database was created and analyzed to identify the location and type of medical institutions in relationship to natural parks. The interest level of these medical institutions in natural parks and environments was added to the database based upon descriptions from within their websites. The results showed that even medical institutions that were approximately 30 km away from natural parks were aware of them. In addition, the medical institutions, especially the mental hospitals and nursing hospitals, where there were many patients who needed long-term treatment were highly interested in natural parks and environments, and their patients’ length of stay exceeded the national average. These findings suggest that medical institutions both inside and outside natural park areas could possibly provide support.