There are included a gas-liquid separator (14) that performs gas-liquid separation on fuel exhaust gas exhausted from a fuel cell (11), a combustion section (13) that combusts hydrogen in the separated fuel exhaust gas, a heat exchanger (15) that performs heat exchange on combustion exhaust gas generated by the combustion, to condense moisture in the combustion exhaust gas and obtain combustion exhaust gas condensed water, and a degasifier (16) that removes carbon dioxide gas from the combustion exhaust gas condensed water and the fuel exhaust gas condensed water separated in the gas-liquid separator (14), and the degassed condensed water is stored in condensed water tank (18).