For the purpose of providing a heating unit being small in size, high in efficiency, long in service life, and high in versatility so as to be easily adaptable to various applications, and providing a heating apparatus that uses the heating unit, the heating unit is configured so that a first glass tube is protected against contaminants and the like using a second glass tube, caps and spacers, a reflective sheet may be disposed in a clearance between the first glass tube and the second glass tube, and the clearance in which the reflective sheet is disposed is sealed using the caps. The heating apparatus uses the heating unit described above as a heat source.