In conventional train position detection methods, the position of a train on a railway is detected using a track circuit. Therefore, the position of the train in the track circuit can be detected only due to the train being on the railway anywhere in the range of the track circuit, and in order to detect a more specific position in the track circuit, installation expenses are incurred for sensors such as wayside beacons, and costs increase. If a GPS or wireless communication device is installed in the onboard system, it is possible to detect the specific train position, but not possible to detect the train position when the device malfunctions or when in environments where the GPS or wireless is unusable. The present invention is characterized in that diagram information, overhead wiring brownout information, and track circuit short-circuited position information, from which it is possible to estimate the train position, is acquired from an operation management system, power management system, or signal syste
