A fixing device includes a rotatable fixing member; a heating source configured to heat the fixing member; an opposing member configured to come into contact with an outer circumferential surface of the fixing member to form a nip portion; and a shielding member configured to block heat from the heating source. The shielding member is configured to rotate about a position different from the center of the heating source so as to be movable between a shielding position and a retraction position. The shielding position is a position where the shielding member comes close to the heating source to block heat from the heating source to the fixing member. The retraction position being a position where the shielding member is retracted away from the shielding position.