An image forming apparatus has sufficient fixing stability and load capacity and being free of sheet jamming and poor image formation. An image forming apparatus includes a transfer voltage applying section for applying a voltage to a transfer section; a transfer current detector for detecting the transfer current flowing through the transfer section; a fixing section for fixing the toner image to fixing position at a predetermined temperature; and a size detector for detecting the size of the recording material. The transfer voltage applying section applies a predetermined transfer voltage, while the recording material passes through the transfer section, so that the transfer current is kept a constant current. When the predetermined transfer voltage is lower than a threshold voltage and the size of the recording material is larger than the predetermined size, the fixing section fixes the toner image at a temperature which is lower than the predetermined temperature.