A fixing device comprising: a fixing rotator over which a recording medium bearing an image is conveyed; a first heater configured to heat the fixing rotator, the first heater configured to generate heat evenly in a maximum conveyance span where the recording medium having a maximum width in a width direction of the recording medium is conveyed, the maximum width being available for the fixing rotator; a second heater configured to heat the fixing rotator and generate heat in the maximum conveyance span, the second heater including: a first portion (102b1) configured to generate heat in a first heat generation amount; and a second portion (102b2) configured to generate heat in a second heat generation amount that is greater than the first heat generation amount of the first portion (102b1); a controller configured to control the first heater and the second heater, wherein the controller is configured to turn on the first heater without turning on the second heater if the controller determines that the recording medium has a decreased width that is smaller than a reference width in the width direction of the recording medium, wherein the controller is configured to turn on at least the first heater if the controller determines that the recording medium has an increased width that is not smaller than the reference width in the width direction of the recording medium, wherein the controller is configured to turn on the first heater and the second heater for a predetermined time period if the controller determines that the recording medium has the increased width in the width direction of the recording medium, wherein the controller is configured to turn off the second heater after the predetermined time period elapses, and wherein the controller is configured to determine the predetermined time period based on a width of the recording medium in the width direction of the recording medium. a fixing rotator over which a recording medium bearing an image is conveyed; a first heater configured to heat the fixing rotator, the first heater configured to generate heat evenly in a maximum conveyance span where the recording medium having a maximum width in a width direction of the recording medium is conveyed, the maximum width being available for the fixing rotator; a second heater configured to heat the fixing rotator and generate heat in the maximum conveyance span, the second heater including: a first portion (102b1) configured to generate heat in a first heat generation amount; and a second portion (102b2) configured to generate heat in a second heat generation amount that is greater than the first heat generation amount of the first portion (102b1); a first portion (102b1) configured to generate heat in a first heat generation amount; and a second portion (102b2) configured to generate heat in a second heat generation amount that is greater than the first heat generation amount of the first portion (102b1); a controller configured to control the first heater and the second heater, wherein the controller is configured to turn on the first heater without turning on the second heater if the controller determines that the recording medium has a decreased width that is smaller than a reference width in the width direction of the recording medium, wherein the controller is configured to turn on at least the first heater if the controller determines that the recording medium has an increased width that is not smaller than the reference width in the width direction of the recording medium, wherein the controller is configured to turn on the first heater and the second heater for a predetermined time period if the controller determines that the recording medium has the increased width in the width direction of the recording medium, wherein the controller is configured to turn off the second heater after the predetermined time period elapses, and wherein the controller is configured to determine the predetermined time period based on a width of the recording medium in the width direction of the recording medium. wherein the controller is configured to turn on the first heater without turning on the second heater if the controller determines that the recording medium has a decreased width that is smaller than a reference width in the width direction of the recording medium, wherein the controller is configured to turn on at least the first heater if the controller determines that the recording medium has an increased width that is not smaller than the reference width in the width direction of the recording medium, wherein the controller is configured to turn on the first heater and the second heater for a predetermined time period if the controller determines that the recording medium has the increased width in the width direction of the recording medium, wherein the controller is configured to turn off the second heater after the predetermined time period elapses, and wherein the controller is configured to determine the predetermined time period based on a width of the recording medium in the width direction of the recording medium.