<p>A rotation angle detection device includes a magnetic rotor having four or more magnetic poles on its surface, a sensor device for detecting a magnetic flux from the magnetic rotor, and an electronic circuit unit which uses a plurality of signals from the sensor device so as to output a rotation angle signal based on the rotation angle of the magnetic rotor. The sensor device has a plurality of spin valve type gigantic magnetoresistive elements (magnetoresistive elements having a fixed layer whose magnetization direction is fixed and a free layer whose magnetization direction rotates in accordance with the magnetic field direction) which output two or more different phase signals from the rotating magnetic field generated in the vicinity of the rotating magnet. The spin valve type gigantic magnetoresistive elements include a first spin valve type gigantic magnetoresistive element having a reference magneto-sensitive direction and a second spin valve type gigantic magnetoresistive element having a magneto-sensitive direction different from the first spin valve type gigantic magnetoresistive element.</p>
