A heat-generating device comprising: a reactor; a wound type reactant installed in the reactor, the wound type reactant having a structure in which a thin wire which is formed from a hydrogen storage metal is spirally wound around a supporting part; a heater configured for heating the wound type reactant, an evacuation unit by which a gas in the reactor is exhausted to the outside, and a gas supply unit configured for supplying any of a deuterium gas, a heavy water gas, a protium gas and a light water gas as a reactant gas into the reactor; wherein the wound type reactant is configured as an electrode for generating a plasma in the reactor, characterised in that a plurality of metal nano-protrusions are present on a surface of the thin wire, each metal nano-protrusion has a nano-size of 1000 nm or less and is formed of a hydrogen storage metal; wherein the metal nano-protrusions are configured to occlude hydrogen atoms due to generation of the plasma in the reactor or heating of the wound type reactant, thus generating heat, wherein the reactor includes a cylindrical portion with opening portions at both ends and wall parts (43b, 43c), wherein the wall parts (43b, 43c) block the opening portions through a gasket to form an enclosed space, wherein a third opening portion and a visual recognition opening portion are provided facing each other on the lateral surface of the cylindrical portion; and a cylindrical pipe communicating portion is provided having one end bonded to the lateral surface of the cylindrical portion so that a hollow region of the pipe communicating portion communicates with the third opening portion, and a third wall part is provided on the other end of the pipe communicating portion; and a gas supply pipe, an evacuation pipe, and a pipe for measuring a pressure are provided in the third wall part, the wound type reactant being arranged in the reactor so as to face the third opening portion and the visual recognition portion and being configured such that the gas sent from the pipe communicating portion can directly be propelled to the wound type reactant. a reactor; a wound type reactant installed in the reactor, the wound type reactant having a structure in which a thin wire which is formed from a hydrogen storage metal is spirally wound around a supporting part; a heater configured for heating the wound type reactant, an evacuation unit by which a gas in the reactor is exhausted to the outside, and a gas supply unit configured for supplying any of a deuterium gas, a heavy water gas, a protium gas and a light water gas as a reactant gas into the reactor; wherein the wound type reactant is configured as an electrode for generating a plasma in the reactor, characterised in that a plurality of metal nano-protrusions are present on a surface of the thin wire, each metal nano-protrusion has a nano-size of 1000 nm or less and is formed of a hydrogen storage metal; wherein the metal nano-protrusions are configured to occlude hydrogen atoms due to generation of the plasma in the reactor or heating of the wound type reactant, thus generating heat, wherein the reactor includes a cylindrical portion with opening portions at both ends and wall parts (43b, 43c), wherein the wall parts (43b, 43c) block the opening portions through a gasket to form an enclosed space, wherein a third opening portion and a visual recognition opening portion are provided facing each other on the lateral surface of the cylindrical portion; and a cylindrical pipe communicating portion is provided having one end bonded to the lateral surface of the cylindrical portion so that a hollow region of the pipe communicating portion communicates with the third opening portion, and a third wall part is provided on the other end of the pipe communicating portion; and a gas supply pipe, an evacuation pipe, and a pipe for measuring a pressure are provided in the third wall part, the wound type reactant being arranged in the reactor so as to face the third opening portion and the visual recognition portion and being configured such that the gas sent from the pipe communicating portion can directly be propelled to the wound type reactant.