To allow installation at low cost to any route, and to accurately detect a train stop position without taking time or labor in maintenance or inspections of a device.

In the detection method of the train stop position P, a distance sensor 3 for irradiating the front surface of a train T during a stop operation with spot-like measurement light 2 while performing scanning in a line shape along right and left directions is used to measure a distance from the distance sensor 3 to the front surface of the train T, and the stop state and stop position of the train T are detected on the basis of the measured distance.