A relationship between a length of a pixel formed by an image drawing operation along a disk circumferential direction, and a length of a pit formed by an data recording operation along the disk circumferential direction is set in such a manner that a plurality of pits are entered to the length of 1 pixel along the disk circumferential direction. While one pixel is being drawn by employing the image drawing beam, within such a section that the power of the data recording beam becomes recording power in order to form the pit, the power of the image drawing beam is temporarily lowered to such a power which does not change the visible light characteristic of the image drawing layer.