To solve a problem wherein device of symbol print becoming assistance guide for safe driving is made on a front windshield of a conventional automobile and it is not easy that it exactly and stably travels on a center in a traveling lane band and driving is performed while retaining a safe left and right side gaps and safe front inter-vehicle distance under the circumstance.

The symbol becoming the assistance guide for exactly and stably traveling on the center in the traveling lane and retaining the safe left and right side gaps and the safe front inter-vehicle distance for avoiding danger is printed on the front windshield in front of front look of the driver. The symbol is that of trapezoid for indicating an advancing own virtual vehicle and constituted by two left and right oblique straight line 1 and straight line 2 for indicating an advancement direction of ground-contact surfaces of left and right tires along an inner side of left and right border lines or the like of the traveling lane band seen from the driver and two upper and lower parallel straight line 3 and straight line 4 perpendicular (namely, horizontal) to the linear advancement direction.