It is an object to provide a thin film magnetic head capable of improving characteristics and properties required of a gap layer by, in particular, appropriately controlling the compositional ratio of a NiPRe alloy used as the gap layer. A NiPRe alloy which has excellent chemical agent resistance, which maintains excellently a non-magnetic state even when heated at a high temperature, and which can suppress the element diffusion at the interface to a magnetic pole layer can be formed through plating by controlling the compositional ratio of the NiPRe alloy used as a gap layer at within the range enclosed by boundary lines A to E in a ternary diagram.