Fixing device having heat applying rotary body and pressure applying rotary body, and image forming apparatus equipped with the fixing device

A fixing device for use in an image forming apparatus which is capable of forming both-side images on a sheet which passes through the fixing device twice by using a sheet reversing and conveying device, the fixing device comprising:

• (a) a heat applying rotary body having an elastic layer made of rubber including at least one layer and further a toner releasing layer on top thereof for coming into contact with and heating a side bearing an unfixed toner image of a transfer sheet;
• (b) a pressure applying rotary body having a second elastic layer made of rubber including at least one layer and further a second toner releasing layer on top thereof for fixing and conveying the transfer material by coming into pressure contact and rotating with the heat applying rotary body;
• and
• (c) a heat applying source for heating at least one of said rotary bodies,
• wherein micro-hardness of the pressure applying rotary body is smaller than that of the heat applying rotary body.