The present invention provides a magnetic sensor capable of reproducing a magnetic record even if the size of a recorded magnetization is a minute one, directly reading a magnetization recorded on a magneto-optical disk without applying incident light itself to the magneto-optical disk, and obtaining signals of a second harmonic having a high S/N ratio. This magnetic sensor includes a magnetic sensor element (102) having electric polarization disposed with respect to a perpendicular recording medium (101), and laser generating means acting on the magnetic sensor element (102). The magnetic sensor reads information in the perpendicular recording medium (101) based on the variation of the rotation angle .phi. of the polarization plane of a second harmonic (105) of a frequency 2.omega. exiting the magnetic sensor element (102) by the application of laser light (104) with a frequency .omega. from the laser generation means to the magnetic sensor element (102).