A hydrogen generation device includes a catalyst; a sulfur-trap member; a soot-trap member; a pair of reformers; and a control portion. In each reformer, a reforming reaction is carried out to generate hydrogen-containing gas using gasoline and cathode off-gas on the catalyst, and an exothermic reaction is carried out to heat the catalyst using anode off-gas and air. The control portion executes a control such that the reactant and the exothermic material are alternately supplied to each reformer, whereby the reforming reaction and the exothermic reaction are alternately carried out in each reformer. A fuel cell system includes the hydrogen generation device.