Even when inertial navigation is performed, whether or not the correction of a value detected by an external sensor is appropriate can be judged, so that a dramatically degraded positioning result is prevented from being outputted. A navigation device (100) comprises a GPS receiver (11), an acceleration sensor (12) for detecting at least two-axis accelerations in an X-axis direction that is the front-back direction of a moving body and a Y-axis direction that is the right-left direction of the moving body, and a at least one-axis angular velocity sensor (13) for detecting the angular velocity in an azimuth direction around a Z-axis orthogonal to the X-axis direction and the Y-axis direction. A sensor detection value appropriate correction judgment module (22) of an integrated calculation module (30) having a CPU or the like finds the product of the value (velocity) obtained by integrating the acceleration detection value in the X-axis direction and the angular velocity detection value in the azimuth direction, acquires the error between the value of the product and the acceleration detection value in the Y-axis direction, and judges whether or not corrections made by the acceleration sensor and the angular velocity sensor are appropriate by judging whether or not the error exceeds a predetermined threshold value.