In a navigation apparatus having a base unit that is fastenable to a vehicle and a front panel unit that is attachable to and detachable from the base unit, it is configured such that there are provided with at least three detectors including a GPS signal receiver, wheel speed sensor and gyrosensor; and the microcomputer of the front panel unit determines the detector or detectors to be used for determining the location of the vehicle in accordance with output condition of the detector or detectors. Since the determination is made based on the output condition of the detector or detectors, the detector(s) used for location determination can be optimally selected to enhance the accuracy of vehicle location determination, while the flexibility of detector use in location determination can be improved in the point that the location determination is not necessarily restricted to use of the three detectors.