An object detection system suitable to be mounted on a vehicle comprising: other-vehicle information acquiring means including multiple detecting means (105, 107) and being configured to acquire multiple other-vehicle information data by using the multiple detecting means (105, 107) wherein the acquired multiple other-vehicle information data are at least the inter-vehicle distance and the relative speed and wherein the multiple detecting means (105, 107) include a short and a long distance sensor (104, 106); identifying means configured to determine whether or not multiple other-vehicle information data acquired by the different detecting means (105, 107) from the short range sensor and the long range sensor correspond to the same vehicle in front of the host vehicle on the basis of a predetermined identification condition; and information selecting means configured to select either of the multiple other-vehicle information data of the long range sensor or the short range sensor determined to be of the same vehicle by the identifying means based on the measured distances and detecting accuracy of the detecting means (105, 107) wherein the information selecting means switches the other-vehicle information data to another other-vehicle information data determined to be of the same vehicle in a transition period characterized in that said information selecting means switches based on a relative speed and a relative distance from the other vehicle, wherein the transition period based on the relative speed and the relative distance from the other vehicle is a period based on a time to a collision obtained by dividing the relative distance by the relative speed. other-vehicle information acquiring means including multiple detecting means (105, 107) and being configured to acquire multiple other-vehicle information data by using the multiple detecting means (105, 107) wherein the acquired multiple other-vehicle information data are at least the inter-vehicle distance and the relative speed and wherein the multiple detecting means (105, 107) include a short and a long distance sensor (104, 106); identifying means configured to determine whether or not multiple other-vehicle information data acquired by the different detecting means (105, 107) from the short range sensor and the long range sensor correspond to the same vehicle in front of the host vehicle on the basis of a predetermined identification condition; and information selecting means configured to select either of the multiple other-vehicle information data of the long range sensor or the short range sensor determined to be of the same vehicle by the identifying means based on the measured distances and detecting accuracy of the detecting means (105, 107) wherein the information selecting means switches the other-vehicle information data to another other-vehicle information data determined to be of the same vehicle in a transition period characterized in that said information selecting means switches based on a relative speed and a relative distance from the other vehicle, wherein the transition period based on the relative speed and the relative distance from the other vehicle is a period based on a time to a collision obtained by dividing the relative distance by the relative speed.