To eliminate complicated adjustment work, to prevent erroneous setting, and to reduce system cost.

When a vehicle type code is input from a controller 100 provided in a vehicle to a direction calculating and processing part 20, a correction factor setting part 210 reads out a correction angle corresponding to the vehicle type code, referring to a table stored in a correction angle storage part 212. The correction angle corresponds to an attaching angle for an angular velocity sensor 6 in the vehicle specified by the vehicle type code, and the correction factor setting part 210 calculates 1/cos using the correction angle to set a correction factor S2. A correction factor adjusting part 204 corrects the angular velocity data using the correction factor S2 and the like, and an integration calculating part 206 integrates the angular velocity data after the correction to calculate a direction of the vehicle.