A metal sheet showing either voltage characteristics, impedance or calorific characteristics close to the case where low frequency is applied even when a high frequency alternating current voltage is applied. This metal sheet presents a good movement of displacement and less starting points of cracking, because of its good crystallinity (good mobility of conductive electrons). Therefore, it is hardly destroyed under the repeated deformation. In short, it presents a high fatigue resistance against repetitive deformation. Therefore, this metal sheet is suited for a fixing belt and a fixing apparatus. The evaluation of fatigue resistance using this can be realized by comparing voltage characteristics, impedance, or calorific characteristics when high and low frequency alternating current voltages are applied to a test piece.