NOVELTY - A hydrogen generating apparatus has adsorption desulfurizer (2) which reduces the concentration of sulfur compound in the raw material, hydrodesulfurization device (10) which reduces the concentration of sulfur compound in the raw material using hydrogen rich gas, reforming reactor (11), 1st raw material path (1) which connects the material supply origin and the adsorption desulfurizer, 2nd raw material path (3) which connects the adsorption desulfurizer and the hydrodesulfurization device, exhaust gas path (4) which discharges hydrogen rich gas, recycle path (7), and on-off valve (8).    USE - A hydrogen generating apparatus for fuel cells.    ADVANTAGE - Condensed water back flow to the adsorption desulfurizer is prevented, and the structure is simple.    DETAILED DESCRIPTION - A hydrogen generating apparatus has adsorption desulfurizer (2) which reduces the concentration of sulfur compound in the raw material supplied from material supply origin, hydrodesulfurization device (10) which reduces the concentration of the sulfur compound in the raw material using hydrogen rich gas, reforming reactor (11) which modifies the raw material discharged from the hydrodesulfurization device, and produces hydrogen rich gas, 1st raw material path (1) which connects the material supply origin and the adsorption desulfurizer, 2nd raw material path (3) which connects the adsorption desulfurizer and the hydrodesulfurization device, exhaust gas path (4) which discharges hydrogen rich gas from the reforming reactor, recycle path (7) which supplies hydrogen rich gas to the hydrodesulfurization device by branching a part of hydrogen rich gas from the 1st branch part in the middle of the exhaust gas path and merging into a merging part (6) in the middle of 2nd raw material path, and on-off valve (8) provided in the 1st raw material path for closing during power supply cut-off. The 2nd raw material path has a path with elevation difference (9) provided between the merging part and the adsorption desulfurizer so that the merging part side is low and the adsorption desulfurizer is high.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the hydrogen generating apparatus. (Drawing includes non-English language text).    1st raw material path (1)    Adsorption desulfurizer (2)    2nd raw material path (3)    Exhaust gas path (4)    Merging part (6)    Recycle path (7)    On-off valve (8)    Path with elevation difference (9)    Hydrodesulfurization device (10)    Reforming reactor (11)