Optical disk apparatus

An information recording/reproducing apparatus that irradiates light to an information recording medium, of which recording layer is formed with a phase change layer, so as to record or reproduce information, comprising:

• a light source;
• a dividing mechanism for diving laser light, which is emitted from said light source and polarized in the same direction, into two light waves, said dividing mechanism including a laser power ratio controller that controls a power ratio at which the laser light is divided, and the two light waves respectively assuming the first power that causes the temperature of said recording layer to be equal to or higher than the melting point, and the power that causes said recording layer to be crystallized;
• a photo-detector for detecting light waves reflected from said information recording medium to which the two light waves are irradiated;
• and
• a signal adding mechanism for converting the reflected light waves of the two light waves, which are detected by said photo-detector, into signals, and adding up the signals.