A magnetoresistive type thin film magnetic head is completely unaffected by external noise and produces only low interference with a recording medium. A magnetoresistive element which constitutes the thin film magnetic head has three terminals constituted by two end terminals and an intermediate terminal. Constant currents which flow in opposite directions are respectively supplied to the two end terminals. A magnetic field of a signal recorded on and reproduced from a single track of the recording medium is applied to the magnetoresistive element, and reproduction outputs of opposite phases appear at the two end terminals. These outputs are differentially amplified by a differential amplifier. Furthermore, the magnetoresistive element is biased by an induced magnetic anisotropy means in a predetermined direction.