PURPOSE: To previously prevent the traffic accident by allowing an automobile in the high speed drive training to be taken account of from the automobies on the periphery.

CONSTITUTION: A basic plate 4 is installed in a demountable manner on the roof 1 of an automobile by a pair of engagement tools 12, aod a protecting case 3 is installed on both the sides of the basic plate 4, and both the surfaces in the frontward and the rearward directions of the automobile of the protecting case 3 are made transparent, and a sign board 6 is fitted into a channel formed oppositely to the upper side inner surface of the protecting case 3 and the upper surface of the basic plate 4, and each display lamp 8 is installed on both the end sides of the sign board 5.