An ink set for ink-jet recording includes a black ink containing a black pigment having an average particle size of from about 100 nm to about 150 nm, and color inks containing color pigments having an average particle size of from about 60 nm to about 90 nm. The objective lens includes a refractive lens whose one surface is divided into a common area through which a light beam of a low NA, which is necessary and sufficient for an optical disc having low recording density, passes and a high NA exclusive area through which a light beam of a high NA, which is necessary only for an optical disc having high recording density, passes. A second embodiment of the invention comprises a method for forming a transistor, having salicided sourcedrain regions, utilizing photosensitive polyimide spacers for forming the salicided sourcedrain regions, without disposing of the spacers. The cover is made of a material having a magnetic conductivity.