PURPOSE: To form a format part adopting a soft format system and having such high reliability that erroneous action is prevented and disorder or erasure is not caused when it is allowed to stand in an environment at a high temp.

CONSTITUTION: This magneto-optical recording medium capable of optically modulated overwriting contains a memory layer, a recording layer, a switching layer and an initializing layer as four magnetic layers laminated on the substrate. A format signal is composed of magneto-optically recorded marks and the direction of magnetization of the initializing layer in the marks corresponding to the format signal is made different from that in the format region except the marks.