Blitzortung.org is a worldwide non-commercial low-cost community based Time of Arrival lightning detection and lightning location network. The aim of this project is to accomplish a low budget high accurate worldwide lightning location network based on a high number of receiver sites spaced close to each other, typically separated by 50 km 250km. The stations transmit their data to a central server, where the strike locations are computed by the arrival times of the signals. The station operators are volunteers who bought and assembled the hardware by themselves. We installed this sensor in more than 24 locations throughout Japan, for example Hokkaido, Tokyo, Okinawa, Ogasawara etc. This paper describes the outline of Blitzortung and the evaluation of the position accuracy.