The purpose of this paper is to clarify the spatial structure in Okinawa Island in terms of accessibility to medical opportunities. Through the analyses of accessibility using network analysis in ARC/INFO, it was found that the spatial structure in Okinawa Island is considered as a system of concentric zone structures. The spatial structure of accessibility to medical opportunities in Okinawa Island changes according to the marginal distance. If the marginal distance is 5 minutes, the spatial structure in Okinawa Island consists of many concentric zones with the centre in Naha, Okinawa city, Nago, etc.. In case of 15 minutes, the spatial structure consists of two concentric zones with the centre in Naha-Okinawa City and Nago. In case of 30 minutes, the spatial structure consists of only one concentric zone with the centre in Naha.