Hydrogen generator and fuel cell system

A hydrogen generator comprising:

• a reformer configured to generate a hydrogen-containing gas through a reforming reaction using a raw material;
• a hydrogen-containing gas passage downstream of the reformer;
• a hydrodesulfurization unit configured to remove a sulfur compound from the raw material;
• a recycle passage configured to flow therethrough the hydrogen-containing gas to be added to the raw material in a state before the raw material flows into the hydrodesulfurization unit, the recycle passage having a downward slope such that at least a portion of the recycle passage is inclined with respect to the hydrogen-containing gas passage;
• and
• a water drain passage configured to discharge condensed water generated in the downward slope of the recycle passage.