Abstract: A direction finder is disclosed, which comprises a locus amending means which operates such that, when corrected detection signal pairs obtained by correcting detection signal pairs after an initial correction on the basis of coordinates value of a center of an ellipsoidal locus and radii thereof in x and y directions are not on a circle in a perpendicular coordinates system corresponding to the ellipsoidal locus, distances from the circle to the coordinates of the corrected detection signal pairs are divided into perpendicular coordinates components as vector component pair and the center coordinates of the ellipsoidal locus and radii thereof are amended and updated on the basis of the vector component pairs and radii, the magnetism detection signal being amended with using these amending values.

Abstract: A direction finder includes a correction amount amending means which amends automatically correction amounts necessary to cancel out an influence of varying magnetization field of a vehicle on the basis of magnetic detection signals obtained before and after the vehicle changes its moving direction by an angle larger than a predetermined value.