A magnetism detection device includes a geomagnetism detection element for detecting geomagnetism of each transverse axial component and a nonvolatile memory element of a thermal metamorphic type for storing one piece or a plurality of pieces of correction data for correcting the detected geomagnetism values. Each piece of correction data is expressed as a value of a ration of inter-axial correction coefficient to the axial sensitivity correction coefficient of either axis.