An obstacle detection system for a vehicle which is capable of detecting nearby and remote objects successfully by use of a combination of electromagnetic wave sensors and ultrasonic wave sensors. The system of the present invention includes a plurality of ultrasonic wave sensors each transmitting an ultrasonic wave around the vehicle and receives a reflected wave thereof for detection of nearby obstacles around the vehicle, and an electromagnetic wave sensor which transmits an electromagnetic wave in a forward direction of the vehicle and receives a reflected electromagnetic wave thereof for detection of a remote obstacle. The system includes a vehicle speed sensor which is provided for sensing the speed of the vehicle. A detection unit detects the presence of a nearby obstacle based upon the reflected ultrasonic wave when the vehicle speed equals a predetermined reference speed or less, and detects the position of a remote obstacle relative to the vehicle only based upon the reflected electromagnetic wave when the vehicle speed exceeds the reference speed. The detection unit issues a nearby signal upon detection of the nearby obstacle and issues a remote signal when the position of the remote obstacle is within a predetermined long distance from the vehicle. A warning unit gives warnings respectively in response to the nearby and remote signals.