A fixing device includes a lateral end heater, disposed opposite a lateral end of an inner circumferential surface of a fixing rotator in an axial direction thereof, to heat the fixing rotator and a thermal conduction aid contacting the fixing rotator and the lateral end heater to conduct heat. The lateral end heater includes a power supply portion disposed outboard from a lateral end of the thermal conduction aid in a longitudinal direction thereof and disposed opposite the inner circumferential surface of the fixing rotator. The power supply portion includes an electrode. A cover covers the power supply portion and includes a cover face disposed opposite the inner circumferential surface of the fixing rotator. A height adjuster adjusts a height of the cover face of the cover and causes the cover face to define an identical plane with a fixing rotator side face of the thermal conduction aid.