An obstacle detection system to be mounted on a mining haulage vehicle, comprising: a first obstacle detection device disposed on the mining haulage vehicle and configured to measure a distance to an object, a second obstacle detection device configured to measure a distance to the object, said second obstacle detection device being disposed on the mining haulage vehicle at a location higher than a location at which the first obstacle detection device is disposed, characterized in that the obstacle detection system further comprises a detection processing device comprising a determination processing unit and an output processing unit, wherein the determination processing unit is programmed to determine, on a basis of detection results of the first obstacle detection device and the second obstacle detection device, whether the object is a small vehicle with a relatively small body frame or is a large vehicle with a relatively large body frame, and the output processing unit is programmed to externally output results of the determination, wherein the first obstacle detection device and the second obstacle detection device have detection directions oriented in a same direction in horizontal planes, respectively, and have detection areas (131, 132) not overlapping each other in a vertical plane in a target distance determination range from the mining haulage vehicle, in which the large vehicle and the small vehicle are desired to be distinguished from each other, and wherein the determination processing unit is programmed to determine the object to be the large vehicle when the second obstacle detection device has also detected the object in an allowable range in which a same vehicle can be regarded to have been detected at different detection points set by using, as a reference, a detection point where the first obstacle detection device has detected the object, but to determine the object to be the small vehicle when the second obstacle detection device has not detected the object in the allowable range set by using, as the reference, the detection point where the first obstacle detection device has detected the object. a first obstacle detection device disposed on the mining haulage vehicle and configured to measure a distance to an object, a second obstacle detection device configured to measure a distance to the object, said second obstacle detection device being disposed on the mining haulage vehicle at a location higher than a location at which the first obstacle detection device is disposed, characterized in that the obstacle detection system further comprises a detection processing device comprising a determination processing unit and an output processing unit, wherein the determination processing unit is programmed to determine, on a basis of detection results of the first obstacle detection device and the second obstacle detection device, whether the object is a small vehicle with a relatively small body frame or is a large vehicle with a relatively large body frame, and the output processing unit is programmed to externally output results of the determination, wherein the first obstacle detection device and the second obstacle detection device have detection directions oriented in a same direction in horizontal planes, respectively, and have detection areas (131, 132) not overlapping each other in a vertical plane in a target distance determination range from the mining haulage vehicle, in which the large vehicle and the small vehicle are desired to be distinguished from each other, and wherein the determination processing unit is programmed to determine the object to be the large vehicle when the second obstacle detection device has also detected the object in an allowable range in which a same vehicle can be regarded to have been detected at different detection points set by using, as a reference, a detection point where the first obstacle detection device has detected the object, but to determine the object to be the small vehicle when the second obstacle detection device has not detected the object in the allowable range set by using, as the reference, the detection point where the first obstacle detection device has detected the object.