A fixing belt substrate for an image forming apparatus is prepared by an electroforming process. The fixing belt substrate contains nickel of prescribed weight percent, phosphorus of from about 0.4 weight percent or more to about 0.7 weight percent or less, sulfur of from about 0.003 weight percent or more to about 0.02 weight percent or less, and carbon of from about 0.012 weight percent or more to about 0.03 weight percent or less.