A system for production of hydrogen and synthetic natural gas, comprising: a synthetic natural gas production unit for producing synthetic natural gas from hydrogen and carbon dioxide by a reverse shift reaction and a methanation reaction; and a hydrogen production unit for producing hydrogen from a hydrogenated aromatic compound by a dehydrogenation reaction; wherein heat is supplied from the synthetic natural gas production unit to the hydrogen production unit so that a reaction heat of the methanation reaction which is an exothermic reaction is used for the dehydrogenation reaction which is an endothermic reaction; characterized in that the synthetic natural gas production unit includes a high temperature synthetic natural gas production unit for performing the reverse shift reaction and the methanation reaction at a high temperature and a low temperature synthetic natural gas production unit for performing the reverse shift reaction and the methanation reaction at a low temperature lower than the high temperature, the low temperature synthetic natural gas production unit being connected downstream in series with the high temperature synthetic natural gas production unit; wherein the high temperature synthetic natural gas production unit performs the reactions at the high temperature of 350 °C to 500 °C, and the low temperature synthetic natural gas production unit performs the reactions at the low temperature of 250 °C to 350 °C; wherein the hydrogen production unit includes: an evaporator for evaporating the hydrogenated aromatic compound using heat supplied by the low temperature synthetic natural gas production unit; a dehydrogenation reaction unit placed on a downstream side of the evaporator in a heat exchanging relationship with the high temperature synthetic natural gas production unit and producing hydrogen, by a dehydrogenation reaction, from the hydrogenated aromatic compound evaporated by the evaporator; and a heater placed between the evaporator and the dehydrogenation reaction unit in a heat exchanging relationship with the high temperature synthetic natural gas production unit and heating the hydrogenated aromatic compound evaporated by the evaporator; and wherein the system further comprises: a first heat exchanger for supplying reaction heat produced by a reaction in the high temperature synthetic natural gas production unit to the dehydrogenation reaction unit and the heater; and a second heat exchanger for supplying reaction heat produced by a reaction in the low temperature synthetic natural gas production unit to the high temperature synthetic natural gas production unit and the evaporator. a synthetic natural gas production unit for producing synthetic natural gas from hydrogen and carbon dioxide by a reverse shift reaction and a methanation reaction; and a hydrogen production unit for producing hydrogen from a hydrogenated aromatic compound by a dehydrogenation reaction; wherein heat is supplied from the synthetic natural gas production unit to the hydrogen production unit so that a reaction heat of the methanation reaction which is an exothermic reaction is used for the dehydrogenation reaction which is an endothermic reaction; characterized in that the synthetic natural gas production unit includes a high temperature synthetic natural gas production unit for performing the reverse shift reaction and the methanation reaction at a high temperature and a low temperature synthetic natural gas production unit for performing the reverse shift reaction and the methanation reaction at a low temperature lower than the high temperature, the low temperature synthetic natural gas production unit being connected downstream in series with the high temperature synthetic natural gas production unit; wherein the high temperature synthetic natural gas production unit performs the reactions at the high temperature of 350 °C to 500 °C, and the low temperature synthetic natural gas production unit performs the reactions at the low temperature of 250 °C to 350 °C; wherein the hydrogen production unit includes: an evaporator for evaporating the hydrogenated aromatic compound using heat supplied by the low temperature synthetic natural gas production unit; a dehydrogenation reaction unit placed on a downstream side of the evaporator in a heat exchanging relationship with the high temperature synthetic natural gas production unit and producing hydrogen, by a dehydrogenation reaction, from the hydrogenated aromatic compound evaporated by the evaporator; and a heater placed between the evaporator and the dehydrogenation reaction unit in a heat exchanging relationship with the high temperature synthetic natural gas production unit and heating the hydrogenated aromatic compound evaporated by the evaporator; and wherein the system further comprises: a first heat exchanger for supplying reaction heat produced by a reaction in the high temperature synthetic natural gas production unit to the dehydrogenation reaction unit and the heater; and a second heat exchanger for supplying reaction heat produced by a reaction in the low temperature synthetic natural gas production unit to the high temperature synthetic natural gas production unit and the evaporator.