To provide a magnetic direction sensor, which indicates the stabilized characteristics without the effect of the change in surrounding environmental conditions.

A bias coil for applying a bias magnetic field on the magnetoresistance element constituting a magnetic sensor, which constitutes the magnetism detecting directions in the reverse directions and comprises the magnetoresistance element as one unitary body, is constituted. Two AC rectangular-wave voltages in opposite phases to each other at the same level are applied. The output voltage of the magnetic sensor 2 at this time is amplified by an amplifier circuit 5 including a bypass filter. The amplified signal is detected by two synchronous detector circuits. The output of the magnetic sensor 2 is obtained through an operator 3 for the difference in the synchronous detected outputs, which operates the two detected synchronous signals. The magnetic sensors 2 are arranged at angle of 90 degrees to each other.