Provided is a magnetic sensor capable of identifying an individual having a high offset voltage, which is a cause of an initial defect in magnetic characteristics, and changes over time. A cross-transmission switch is provided in a changeover switch circuit which transmits to an amplifier circuit a differential signal voltage output from a Hall element, and the cross-transmission switch cross-transmits a signal in any one of a first period and a second period during which a current flowing into the Hall element is switched by a control signal from a control circuit, to thereby determine and identify a magnitude of an offset voltage.