The present invention provides a thin film magnetic head and a method of manufacturing the same in which a magnetic sensitive layer can be formed as a single magnetic domain while adapting the head to higher recording density and, further, which can display a higher resistance change rate. While narrowing the magnetic sensitive layer, a vertical bias magnetic field having both sufficient intensity and uniformity can be applied to the magnetic sensitive layer. As a result, it can be promoted to form the magnetic sensitive layer as a single magnetic domain while adapting the head to higher recording density, so that reading operation can be performed more stably. Particularly, in the case of passing sense current in the thickness direction to an MR film, a higher magnetoresistive change rate can be obtained.