An image forming apparatus comprising: an image forming unit configured to perform image forming on a surface of a sheet by using a non-decolorable first toner or a decolorable second toner; a fixing device configured to heat and fix an image, by the first toner, which image is formed on the surface of the sheet at a first fixing reference temperature, or to heat and fix an image, by the second toner, which image is formed on the surface of the sheet at a second fixing reference temperature different from the first fixing reference temperature; and a control circuit configured to acquire a selection signal indicating which mode is selected from among a first mode in which the image is formed using the first toner, a second mode in which the image is formed using the second toner, and a third mode in which the image is erased by heating the sheet on which the image is formed by the second toner using the fixing device at a decolorizing temperature, set a standby temperature in accordance with the mode indicated by the selection signal, and control a temperature of the fixing device to be the standby temperature, wherein the control circuit is configured to acquire the selection signal, set the standby temperature, and control the temperature of the fixing device before an operation of the mode selected by the selected signal starts, characterized in that when a reference temperature is set to be the first fixing reference temperature when the first mode is selected, is set to be the second fixing reference temperature when the second mode is selected, and is set to be the decolorizing temperature when the third mode is selected, the control circuit is configured to perform changing the standby temperature to the reference temperature when the selection signal indicating that the mode different from the current mode is selected is acquired a predetermined number of times, the number of times being two or more times. an image forming unit configured to perform image forming on a surface of a sheet by using a non-decolorable first toner or a decolorable second toner; a fixing device configured to heat and fix an image, by the first toner, which image is formed on the surface of the sheet at a first fixing reference temperature, or to heat and fix an image, by the second toner, which image is formed on the surface of the sheet at a second fixing reference temperature different from the first fixing reference temperature; and a control circuit configured to acquire a selection signal indicating which mode is selected from among a first mode in which the image is formed using the first toner, a second mode in which the image is formed using the second toner, and a third mode in which the image is erased by heating the sheet on which the image is formed by the second toner using the fixing device at a decolorizing temperature, set a standby temperature in accordance with the mode indicated by the selection signal, and control a temperature of the fixing device to be the standby temperature, wherein the control circuit is configured to acquire the selection signal, set the standby temperature, and control the temperature of the fixing device before an operation of the mode selected by the selected signal starts, set a standby temperature in accordance with the mode indicated by the selection signal, and control a temperature of the fixing device to be the standby temperature, wherein the control circuit is configured to acquire the selection signal, set the standby temperature, and control the temperature of the fixing device before an operation of the mode selected by the selected signal starts, characterized in that when a reference temperature is set to be the first fixing reference temperature when the first mode is selected, is set to be the second fixing reference temperature when the second mode is selected, and is set to be the decolorizing temperature when the third mode is selected, the control circuit is configured to perform changing the standby temperature to the reference temperature when the selection signal indicating that the mode different from the current mode is selected is acquired a predetermined number of times, the number of times being two or more times. when a reference temperature is set to be the first fixing reference temperature when the first mode is selected, is set to be the second fixing reference temperature when the second mode is selected, and is set to be the decolorizing temperature when the third mode is selected, is set to be the first fixing reference temperature when the first mode is selected, is set to be the second fixing reference temperature when the second mode is selected, and is set to be the decolorizing temperature when the third mode is selected, the control circuit is configured to perform changing the standby temperature to the reference temperature when the selection signal indicating that the mode different from the current mode is selected is acquired a predetermined number of times, the number of times being two or more times.