A heating device for being attached to and heating a heated object that requires to be heated and has an uneven exterior shape. The heating device including: a conductive member having thermal conductivity and being configured to be attached to a recess of the heated object; and a heater configured to cover and heat the heated object and the conductive member in a state where the conductive member is attached to the recess of the heated object. The heater has a portion to be in contact with a bulge portion of the heated object in a state where the conductive member is attached to the recess of the heated object and where the heated object and the conductive member are covered with the heater.