In 2011, Japan experienced a major catastrophe: The Great East Japan Earthquake and subsequent tsunami. After the tsunami struck, overland transport routes were cut off, and consequently, emergency supplies and people requiring medical attention could not be transported very efficiently. Many hospitals and other emergency facilities were destroyed or were operating with reduced capabilities during this period, meaning victims could not receive treatment within a reasonable timeframe. Therefore, we need to consider emergency facilities, particularly for medical support, which are resilient and versatile for use in such situations. Floating bases for disaster relief and support ships are already available for deployment along coastal regions or on rivers near affected areas. A medical support floating base has also been proposed, which is called the Medi-float hereafter, in preparation for the anticipated Tokyo Inland Earthquake. And it is determined that the primary function of this Medi-float should be as a dialysis treatment center during normal operation and primarily for the treatment of crush syndrome patients during a disaster. But the original proposal was deemed inadequate in terms of facility scale and selection of the suitable site of Medi-float. Therefore, in this research aiming at realization of Medi-float, firstly the number of people who develop crush syndrome in the target area is estimated by GIS based on the damage prediction of the huge earthquake striking Tokyo and the risk of building collapse. Based on the distribution of dialysis treatment facilities and data such as road network data in Tokyo, Voronoi diagrams were created using GIS. And facility scale required for Medi-float and suitable installed site were examined by the distribution of crushed syndrome patients obtained by analysis and Voronoi diagram.