A fixing apparatus for fixing visible images formed on a recording medium has a heat roller having a heating member in the inner portion of the heat roller, and a flat plate-like elastic member forming a nip in contact with the heat roller and capable of exerting a pressure at the nip portion by an elastic stress, the recording medium being fed into the nip portion. According to the fixing apparatus and the fixing method using this apparatus, since a pressure roller is not necessary, the system can be simplified, which leads to miniaturization of the overall fixing apparatus, reduction of overall weight and cost reduction.