A fixing device includes at least one heater disposed opposite an inner circumferential surface of an endless rotary body to heat the endless rotary body and a shield interposed between the endless rotary body and the at least one heater to shield the endless rotary body from heat radiated from the at least one heater. A first size recording medium passes over a first passage region of the endless rotary body and a second size recording medium passes over a second passage region of the endless rotary body. The shield includes a notch disposed opposite a lateral end of the second passage region of the endless rotary body in an axial direction thereof. The lateral end of the second passage region overlaps a non-passage region of the endless rotary body in the axial direction thereof where the first size recording medium does not pass.