Disclosed is an obstacle detection system of a vehicle. The obstacle detection system includes a driving information unit configured to calculate driving position information of the vehicle, a determiner configured to anticipate whether or not the vehicle will enter a joining point where the vehicle meets a target road to be joined based on the driving position information calculated by the driving information unit, a sensing unit configured to sense obstacles located beside the vehicle, and a controller configured to change a sensing range of the sensing unit so as to detect an obstacle moving on the target road to be joined, when the determiner anticipates that the vehicle will enter the joining point.