PURPOSE: To prevent an accident at a crossing by loading an inter-car distance sensor and a microcomputer and providing a means to raise an alarm when it is judged that approach to the crossing is dangerous.

CONSTITUTION: When a car A approaches a crossing 1a, a receiver 21 loaded onto the car A receives the chrominance signal of a signal 2 at the crossing 1a, remaining time until switching the chrominance signal, car speed, the acceleration and deceleration of the car and distance between cars and this information is inputted to a microcomputer 22 so as to judge whether the approach to the crossing 1a in the driving state is dangerous or safe. When the approach is judged dangerous, the alarm is raised to the driver. Thus, the accident at the crossing can be prevented without fail by preventing the signal confirmation miss of driver, the estimation and the error of judgement of the signal switching time and the error of judgement of the car speed and the distance to the crossing or the like.