In a fixing apparatus and an image forming apparatus of the present invention, an external heating section is provided that includes: an external heating belt; two heat rollers suspending the external heating belt and pressed against a fixing roller via the external heating belt; and a release/contact mechanism for causing the two heat rollers to separate from or contact with the fixing roller. With the heat rollers separated from the fixing roller by the release/contact mechanism, the external heating belt and the fixing roller are in contact with each other and the external heating belt follows rotation of the fixing roller. As a result, a fixing apparatus is provided that includes an external release/contact mechanism that can quickly operate in a small space and at low power without encouraging deterioration of the belt member. An image forming apparatus provided with such a fixing apparatus is also provided.