A fixing device includes a heat conductive member; a flexible fixing belt looped around the heat conductive member, an inner circumference of the flexible fixing belt slidably contacting a portion of an outer circumferential surface of the heat conductive member; a rotary pressing member disposed opposing the heat conductive member; heat sources disposed in a circumferential direction of the fixing belt at a predetermined interval to heat the heat conductive member; and temperature detectors provided to detect a surface temperature of the fixing belt at a detection position at which heating intensity of a corresponding one of the heat sources is not affected by any other one. In operation, the inner circumferential surface of the fixing belt contacts the heat conductive member at a position at which each temperature detector contacts the fixing belt as the detection position or a position proximal to the detection position of each temperature detector.