An image forming apparatus comprising: a plurality of chargers that each charge an image carrier, respectively; a plurality of developing devices that each form a toner image on the respective charged image carrier; and a fixing device that fixes the toner image, transferred from the image carrier to a recording medium (2a, 2b), to the recording medium (2a, 2b), wherein the fixing device includes a fixing rotation body (51, 23, 203), a heat application source (56, 24, 202) that heats a portion of the fixing rotation body (51, 23, 203), and a pressing rotation body (58, 22, 202) that forms a nip between the pressing rotation body (58, 22, 202) and the fixing rotation body (51, 23, 203) and that transports the recording medium (2a, 2b), characterized by a controller configured to set, in the heat application source (56, 24, 202), a standby temperature in a standby state in which rotation of the fixing rotation body (51, 23, 203) is suspended is set to be higher than a printing temperature in a printing state, and, in the fixing device, the heat application source (56, 24, 202 is always on during a preparation period after starting the printing state in response to receiving a printing instruction, in the fixing device, the fixing rotation body (51, 23, 203) is set to rotate at a first speed in the printing state and rotate at a second speed during the preparation period, and the second speed is set to be less than or equal to the first speed, and in the fixing device, a setting temperature of the heat application source (56, 24, 202) is set to be changed in accordance with a speed ratio of the first speed and the second speed, the setting temperature being set after starting the printing state in response to receiving the printing instruction a plurality of chargers that each charge an image carrier, respectively; a plurality of developing devices that each form a toner image on the respective charged image carrier; and a fixing device that fixes the toner image, transferred from the image carrier to a recording medium (2a, 2b), to the recording medium (2a, 2b), wherein the fixing device includes a fixing rotation body (51, 23, 203), a heat application source (56, 24, 202) that heats a portion of the fixing rotation body (51, 23, 203), and a pressing rotation body (58, 22, 202) that forms a nip between the pressing rotation body (58, 22, 202) and the fixing rotation body (51, 23, 203) and that transports the recording medium (2a, 2b), characterized by a fixing rotation body (51, 23, 203), a heat application source (56, 24, 202) that heats a portion of the fixing rotation body (51, 23, 203), and a pressing rotation body (58, 22, 202) that forms a nip between the pressing rotation body (58, 22, 202) and the fixing rotation body (51, 23, 203) and that transports the recording medium (2a, 2b), characterized by a controller configured to set, in the heat application source (56, 24, 202), a standby temperature in a standby state in which rotation of the fixing rotation body (51, 23, 203) is suspended is set to be higher than a printing temperature in a printing state, and, in the fixing device, the heat application source (56, 24, 202 is always on during a preparation period after starting the printing state in response to receiving a printing instruction, in the fixing device, the fixing rotation body (51, 23, 203) is set to rotate at a first speed in the printing state and rotate at a second speed during the preparation period, and the second speed is set to be less than or equal to the first speed, and