To instantly inform an abnormal portion to an occupant by alarm sound on an obstacle detection system for a vehicle.

This alarm device for the vehicle has speakers 41-44 to generate the alarm sound and a clearance sonar 10 to detect an obstacle in the circumference of the vehicle, a DSP 21 discriminates a setting position of the sensor detecting the obstacle in accordance with sonar output from this clearance sonar (hereinafter called detected sensor position), arranges a virtual sound source at a position of this discriminated detected sensor position and controls the speakers 41-44 so as to make it possible for the occupant of the vehicle to hear the alarm sound from the virtual sound source.