In a paper conveyer of an image forming apparatus, a transfer operation is performed by a transfer roller and an unfixed image in the transfer operation is carried onto the lower side of a transfer paper sheet. The transfer paper sheet is conveyed to a fixing device constructed by a fixing roller and a pressurizing roller. A hardness of the fixing roller is smaller than that of the pressurizing roller, while a nipping portion of the fixing and pressurizing rollers is formed in a concave shape. The fixing and pressurizing rollers are arranged such that a nipping inlet port point of the fixing and pressurizing rollers is located in the vicinity of a line of a conveying locus of a thin transfer paper sheet. A paper guide plate guides the transfer paper sheet to the nipping inlet port. In this construction, a transferred paper sheet is conveyed such that this transferred paper sheet is reliably fed into the nipping portion of the fixing device, and it is possible to prevent an image rub, wrinkles, a jam, etc. from being caused.