A vehicle recognition allowing device is provided which allows the recognition of a traveling state of a vehicle, including a two-wheeled vehicle to be recognized and does not require a sophisticated image processing function. When a change in the speed, traveling state or both of the vehicle is detected by a traveling state detecting part, flickering frequencies of respective infrared ray markers are increased or decreased to a frequency corresponding to the change in speed, traveling state or both. Alternatively, flickering duty ratios of the respective infrared ray markers can be changed to a duty ratio corresponding to the new speed, traveling state or both.