a magnetic head having a magnetoresistive head having a spin valve structure in which a composite magnetic layer of a rotatable magnetizing direction layer and oxide or the like is used for a lower shielding layer and / or an upper shielding layer and a magnetic disk apparatus using such a head are disclosed . according to the invention , a magnetic head having a head of a magnetoresistance effect type generating a high output with low noises and a magnetic disk apparatus having a large quantity with high recording density can be realized .