An axis misalignment determining apparatus is configured to determine an axis misalignment in a sensor mounted on a vehicle by using a determining member mounted on the vehicle. The axis misalignment determining apparatus is provided with: a storage configured to store therein a result of detection of the determining member by the sensor in a condition in which there is no axis misalignment, as a detection result in a normal case; an acquirer configured to detect the determining member by using the sensor and configured to obtain it as a present detection result; and a determinator configured to determine whether or not there is an axis misalignment in the sensor by comparing the present detection result with the detection result in the normal case.