A thin-film magnetic head that the TPTP phenomenon due to the environment temperature is surely suppressed without providing a new particular component is provided. The thin-film magnetic head is provided, which includes, an electromagnetic coil element for writing data with a coil layer which generates magnetic field by current flowed in its own and a coil-insulating layer which surrounds the coil layer; and an overcoat layer formed in such a way as to cover the electromagnetic coil element, a width of a track-width direction of the coil-insulating layer being larger than a width that is a minimum width to need to insulate the whole coil layer, and being at least 46 μm, a length of a direction perpendicular to the track-width direction of the coil-insulating layer being larger than a length that is a minimum length to need to insulate the whole coil layer, and being at least 75 μm, a heat expansion coefficient of the coil-insulating layer being larger than or equal to 30×10−6/K, and a Young's modulus of the coil-insulating layer being larger than or equal to 1 GPa and smaller than or equal to 4 GPa.