A vehicle running state judging apparatus calculates the edge detecting position of the first pixel group detected by the first gray value detection section, the edge detecting position of the second pixel group based on the gray value at that position, and the gray value at that position and judges meandering of a vehicle by comparing the edge detecting position of the second pixel group detected by the second gray value detection section and the gray value at that position, with the edge detecting position of the second pixel group calculated by the calculation section and the gray value at that position.