Objects of the present invention are to provide an endless metal belt superior in flexing resistance and durability, to provide a fixing belt using the endless metal belt, and to provide a heat fixing device with high durability and high reliability. The objects are achieved by the endless metal belt formed of a nickel alloy containing 5% by weight or more of an additional metallic element and having a half-value width of an X-ray diffraction peak in a range of 0.5 degrees to 2 degrees for each of a crystal plane and a crystal plane, and by using the same.