Japan enacted the Disaster Countermeasures Basic Law in 1961. Article 55 of this Law specifies notices etc. to be made by prefectural governors, and stipulates that an instant command transmission system to all locations in a prefecture relying on radio communications be constructed as one of key facilities for communicating such notices. Recently, many local governmental organizations have equipped themselves with IP infrastructure facilities to provide disaster and administrative information adapted to the latest ICT. JRC has been developing systems meeting such needs. In Kumamoto Prefecture, JRC has constructed a disaster information network and a prefecture-wide command system using this network which links prefectural bureaus, regional development bureaus, prefectural outpost agencies, municipal governmental offices, and fire departments. This is a report on this prefecture-wide command system using this disaster information network.