An image forming apparatus (1) includes an imaging section (2) and a thermal fixing device (20). The fixing device fuses a toner image formed by the imaging section onto the recording sheet (S) passing through a fixing nip. The fixing device includes a fixing member (24), a pressure member (21), a heater (30), a temperature sensor (25), and a temperature controller (26). The fixing member is rotatable, and the pressure member is pressed against the fixing member to form the fixing nip therebetween. The heater heats at least a portion of the fixing member. The temperature sensor senses a temperature of the fixing member. The temperature controller controls the temperature of the fixing member in at least one of an on-off mode and a PID mode. The temperature controller initially operates in the on-off mode upon entering recovery, and switches to the PID mode when a threshold time has elapsed after entering recovery.