An image forming apparatus includes a temperature sensor, a memory, a fixing device, and a controller. The temperature sensor is configured to detect a temperature of an inside of the image forming apparatus. The memory is configured to store temperature history information regarding a history of the temperature of the inside of the image forming apparatus detected by the temperature sensor. The fixing device is configured to fix a toner image onto the paper sheet by heating the paper sheet to a fixing temperature. The toner image is transferred to the paper sheet using a toner stored in a toner cartridge of the image forming apparatus. The controller is configured to control a fixing temperature at the fixing device based on the temperature history information stored in the memory.