A magnetic-sensor controller includes an input section, a perpendicular-bisector calculation section, a storage section, and a setting section. The input section successively inputs a plurality of magnetic data sets successively output from a three-dimensional magnetic sensor. Each magnetic data includes three components. The perpendicular-bisector calculation section calculates, for each pair of two of the magnetic data sets, a perpendicular bisector of two points corresponding to the two magnetic data sets. The storage section stores a plurality of perpendicular bisectors. The setting section statistically approximates, by a single point, a region where the plurality of perpendicular bisectors stored in the storage section meet, and sets an offset of the magnetic data set on the basis of the single point. The magnetic-sensor controller enables accurate setting of an offset even when the magnetic field strength changes.