An image forming apparatus includes an image forming mechanism, a fixing roller, a heater, a sensor, a warm-up mechanism, and a controller. The image forming mechanism forms a toner image on a recording medium according to image data. The fixing roller fixes the toner image on the recording medium by applying heat. The heater heats the fixing roller to warm up the fixing roller. The sensor detects a temperature of the fixing roller. The warm-up mechanism warms up the fixing roller by using the heater. The controller performs a first warm-up control that finishes the warm-up of the fixing roller and a second warm-up control that continues the warm-up of the fixing roller.