A hydrogen generator (100) of the present invention includes: a raw material supplying device (4) configured to supply a raw material containing a sulfur constituent; a hydrogen supplying device (7) configured to generate hydrogen by electrolysis of water; a hydro-desulfurizer (5) configured to remove the sulfur constituent of the raw material by using the hydrogen generated by the hydrogen supplying device (7), the raw material being supplied from the raw material supplying device (4); and a reformer (1) configured to generate a hydrogen-containing gas by a reforming reaction of the raw material from which the sulfur constituent is removed by the hydro-desulfurizer (5).