The invention provides a magnetic recording and reproducing apparatus having magnetic field applying unit applying a magnetic field to a magnetoresistive element to correct a misaligned magnetization direction of the magnetoresistive element. The magnetic field applying unit can be used to correct a misaligned magnetization direction of a free layer of a giant magnetoresistive element. A magnetic field applying unit controller controls the magnetic field applying unit to adjust a magnetization direction and intensity of a magnetic field of the giant magnetoresistive element. The magnetic field applying unit controller can control the magnetic field applying unit to apply a magnetic field only during a data reading time, and to increase the intensity of the application magnetic field during a data re-reading time. The magnetic field applying unit is mounted, corresponding to a head on a suspension that supports a head slider, on a surface of the suspension opposite to the surface on which the head is mounted.