A navigation apparatus mounted on a vehicle is equipped with a first gyro sensor and a second gyro sensor arranged in symmetry with respect to a first axis in a travel direction of the vehicle and to a second axis that passes through the center of gravity of the vehicle, the first and second axes being perpendicular to each other, so that the first and second gyro sensors lean by the same angle from the second axis in opposing directions with respect to a third axis that is perpendicular to the first and second axes. A sensor output circuit is connected to each of the first and second gyro sensors, to output an output signal. A calculator calculates a yaw angular velocity of the vehicle based on the output signal.