This invention provides an on-vehicle electronic apparatus, which has a wireless communication unit which makes a wireless communication via a wireless LAN, means for acquiring position information and velocity information of vehicles before and after the self vehicle using the wireless communication unit, means for calculating the inter-vehicle distances between the self vehicle, and the vehicles before and after the self vehicle with reference to map information on the basis of the acquired position information and velocity information, and means for, when the calculated inter-vehicle distances are equal to or smaller than a predetermined distance and the velocities of the self vehicle and the vehicles before and after the self vehicle are equal to or higher than a predetermined velocity, taking a collision avoidance measure.