A heating device includes a hollow portion that has an endless loop shape in a rotation direction and that has open ends in a rotation-axis direction, at least one heating unit that includes a heat-generating portion and that is inserted in the hollow portion, the heating unit being configured to heat the hollow portion from a space enclosed by the hollow portion as a result of heat generation of the heat-generating portion, and a driving-force transmission unit that is fixed to an end portion of the hollow portion in the rotation-axis direction and that transmits a driving force, which is transmitted to the driving-force transmission unit by a driving source, to the hollow portion so as to rotate the hollow portion, the driving-force transmission unit having an opening that is in communication with an interior of the hollow portion. The heat-generating portion is disposed at a position that does not overlap the driving-force transmission unit in the rotation-axis direction.