A magnetic head has less variations in the resistance of a magneto-resistive device before and after the magnetic head is left in a high temperature environment so as to have higher stability of the characteristics of the magnetic head against a high temperature environment. A TMR device includes a tunnel barrier layer made of an oxide layer. A DLC film serving as a protection film and an underlying layer therefor are formed on an end face of the TMR device on an air bearing surface side. A layer made of an oxide of a metal or an oxide of a semiconductor is formed between the underlying layer and the end face of the tunnel barrier layer on the air bearing surface side to be in contact with the end face of the tunnel barrier layer.