A fuel reforming device includes a combustion part including a burner; an exhaust part configured to circulate an exhaust gas that is generated from the combustion part; and a reactor that is configured to generate hydrogen from a raw material by absorbing heat from the exhaust gas circulating in the exhaust part. The reactor includes a heat storage member that is configured to absorb the heat from the exhaust gas during operation of the combustion part, store the absorbed heat, and provide the absorbed heat to the reactor.