Light emitted from a light source is converged by an objective lens, and an auxiliary lens increases an effective numerical aperture to project the light on a recording medium. The temperature of a recording mark recording on the recording medium is increased by the projection of the light, and saturation magnetization which is in accordance with the information is generated, thus generating magnetic flux. There is a reproducing magnetic layer, which is provided on the auxiliary lens. Magnetization generated on the reproducing magnetic layer has an effect on the polarization direction of the reflected light at the reproducing magnetic layer. Reflected light from the reproducing magnetic layer reaches a photodetector to generate a reproduced signal.