To provide an image forming device equipped with a medium conveying mechanism capable of warping a printing medium curled by a fixing device in an opposite direction sufficiently for correction.

In this image forming device, a developer image 209 formed on the printing medium 101 is fixed by the fixing device 103 and the printing medium 101 is delivered by a post process side medium conveying roller 204, the fixing device 103 is arranged so that a heating member 205 for heating the printing medium 101 and a pressurizing member 206 for pressurizing pressure-contact with each other, and the printing medium 101 passes between the members 205 and 206, and thereby, the developer image 209 is fixed. Post process side medium conveying mechanisms 201 to 204 for conveying the printing medium 101 while continuously or intermittently warping the printing medium 101 in the direction opposite from the direction the printing medium 101 is curled by the heat processing and pressure processing of the fixing device 103 are disposed in a conveying passage from the fixing device 103 to the post process side medium conveying roller 204.