To provide an inter-vehicle distance alarm device reflecting the caution level of a driver while he/she is driving a vehicle.

It is taken notice that the caution level of the driver can be estimated by map information in which a vehicle is located. A position P of a self vehicle, speed v of the self vehicle and a distance d between the self vehicle and a preceding vehicle are detected by a GPS 1, a speed sensor 2 and an inter-vehicle distance sensor 3, respectively, to be outputted to a microprocessor 5. In the microprocessor 5, the position P is collated with a map 4 to decide whether or not the driver is located at a position where attentiveness of the driver is estimated to be high or whether or not the driver is located at a position where attentiveness of the driver is estimated to be low. A threshold value of an alarm is changed according to the decision, and when a degree of emergency obtained from the speed v and the distance d from the preceding vehicle exceeds the threshold value of the alarm, a display instruction is outputted to a display device 6. Since the threshold value of the alarm is changed according to the position P, this inter-vehicle distance alarm device reflects the caution level while the driver drives the vehicle.