According to the present invention on a magnetoresistance device having a magnetoresistance effect element, since iron oxide FeO.sub.x exhibiting antiferromagnetism is used as a pinning layer, a spin-valve type magnetoresistance effect element can be obtained which is particularly excellent in corrosion resistance and has a magnetoresistance ratio with an MR slope no less than 0.7% Oe in the region of the high-frequency magnetic field of 1 MHz. Further, the rise-up characteristic of an MR curve at the zero magnetic field is extremely excellent with small hysteresis, and it has high heat resistance. The heat resistance is further improved by interposing an oxygen blocking layer between the pinning layer and a ferromagnetic layer. In the magnetoresistance device, for example, an MR head, using the magnetoresistance effect element having a magnetic multilayer film, an output voltage is approximately five times as high as that of the conventional material. Accordingly, there can be provided an excellent MR head which has extremely high reliability and enables the reading for ultrahigh density magnetic recording exceeding 1 Gbit/inch.sup.2.