To provide a train accident prevention system for moving an obstruction to a safety zone when the obstruction intrudes in a railway and for preventing a train accident without stopping a train.

A monitor device 5 watches intrusion of the obstruction 4 into a predetermined region of the railway 3 and, when detects the intrusion of the obstruction 4, outputs obstruction intrusion information to an obstruction intrusion information outputting means 6. The means 6 controls an obstruction moving means 8 and quickly moves the intruding obstruction 4 to the safety zone 7 under a floor of the platform 2. After evacuation of the obstruction 4 to the safety zone 7 is checked, the means 8 is returned to an initial position and then the train passes through. A train accident is thus prevented without stopping the train.