To recognize an accurate present position before and after leaving from a parking lot by inhibiting a map matching operation by referring to a state at the time of turning OFF a power source immediately before at the time of turning ON the power source.
A result deciding unit 22 of a main CPU 20 decides a matching state of a present position of an own vehicle with a road based on a processed result of a map matching processor 21. When the unit 22 decides that the own vehicle is located out of a present road, a parking flag is set by a flag/data setter 23, while when the unit 22 decides that the vehicle is located on the road, the flag is cleared, and the set flag is stored in a nonvolatile memory 17. This process is repeated until a power source is turned OFF. If the flag is ON immediately after the power source is turned ON, the present position is stored in a parking lot register, and a map matching inhibit flag is turned ON. When a difference between the present position and a position stored in the lot register is a predetermined value (e.g. 100 m) or more, the map matching is inhibited. Thus, an error of a calculated position according to an erroneous matching is reduced.
MIKUCHI RYOSUKE
KITAMURA YOSHIYUKI
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