Abstract: In a heating device used for melting snow on a road, a roof or the like, or for room heating of in-door facilities, in order to heat a to-be-heated or heated object uniformly over its entire area and enable to utilize effectively a PTC heater, a heat diffusing plate 14 for diffusing heat generated from a heat generating body 16 is arranged on an upper face of the heat insulating member 12 and the heating body 16 is arranged in a recess portion 13 installed on its upper face. The heating body 16 is constituted by inserting a heat generating element 4 mounted with heat radiating plates 5 into a vessel 2 enclosed with a heat storing agent 3 of a latent heat absorbing type in a state in which the heat generating element is brought into contact with the heat storing agent 3.