This invention provides a high sensitivity magnetic head using magneto-resistive effect elements consisting of ferromagnetic thin plates and allows construction of a high precision multi-track head by using thin film and photo-etching techniques. The magnetic head comprises a base, two flux converging cores forming a magnetic gap, a detecting portion provided between the two flux converging cores and extending at right angles to the end of the base, one end of the detecting portion being located in the neighborhood of the gap and having a smaller sectional area than the other portions, and detecting electrodes provided at the opposite ends of the detecting portion. At least one of the two cores is of a ferromagnetic material and integrally formed on the base.