NOVELTY - A hydrogen generating apparatus (200) comprises modifier (1) which produces hydrogen-containing gas by reforming reaction using source gas, hydrodesulfurization device (2) which removes sulfur compound in source gas supplied to modifier, hydrogen-containing-gas flow path (4) which flows hydrogen-containing gas, source gas which passes through source gas flow path (3), ejector (100) which has mixing part for mixing hydrogen-containing gas, recycle gas flow path (5) which supplies a part of hydrogen-containing gas to ejector, and throat part arranged more downstream than mixing part of ejector.    USE - A hydrogen generating apparatus for fuel cell system (claimed).    ADVANTAGE - The hydrogen generating apparatus and the fuel cell system can perform stable hydrodesulfurization reaction in the hydrodesulfurization device while preventing water clogging in an ejector and preventing pulsating current.    DETAILED DESCRIPTION - A hydrogen generating apparatus comprises modifier which produces hydrogen-containing gas by reforming reaction using source gas, hydrodesulfurization device which removes sulfur compound in source gas supplied to modifier, hydrogen-containing-gas flow path which flows hydrogen-containing gas produced with modifier, source gas which passes through source gas flow path, ejector which has mixing part for mixing hydrogen-containing gas that passes through hydrogen-containing gas flow path and supplied to hydrodesulfurization device, recycle gas flow path which branches from hydrogen-containing gas flow path and supplies a part of hydrogen-containing gas to ejector, and throat part arranged more downstream than mixing part of ejector and is down-gradient with respect to gravitational direction from upstream to a downstream. An INDEPENDENT CLAIM is included for fuel cell system comprising hydrogen generating apparatus and fuel cell which produces electric power using the hydrogen-containing gas supplied from hydrogen generating apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of the hydrogen generating apparatus. (Drawing includes non-English language text).    Modifier (1)    Hydrodesulfurization device (2)    Source gas flow path (3)    Hydrogen-containing-gas flow path (4)    Recycle gas flow path (5)    Ejector (100)    Hydrogen generating apparatus (200)