An object of the present invention is to provide a positioning device which can more reliably and frequently correct a own vehicle position earlier, reliably detect an error matching state or a straying state earlier and correct the position to a correct position. The positioning device according to the present invention includes a GPS receiver, a GPS position calculating unit which calculates pseudo distances to the GPS satellites based on the transmission signals, and calculates a re-calculated GPS position which is the own vehicle position based on the pseudo distances, and a multipath influence evaluating unit which evaluates a multipath influence on the GPS position based on a difference between the GPS position calculated by the GPS receiver and the re-calculated GPS position calculated by the GPS position calculating unit.