NOVELTY - A hydrogen generating apparatus (51) for generating hydrogen from ammonia, comprises an ammonia oxidation part (10) having an ammonia oxidation catalyst (11a, 11b) which oxidizes ammonia, and an ammonia decomposition part (20) having an ammonia decomposition catalyst (21) which decomposes ammonia to generate nitrogen and hydrogen; where the ammonia decomposition part is located downstream of the ammonia oxidation part in a direction of feed gas flow.    USE - As hydrogen generating apparatus for generating hydrogen from ammonia; used in fuel cell or internal combustion engine system (claimed), used for ammonia combustion engines using ammonia as a fuel, particularly for ammonia combustion engines for automobiles.    ADVANTAGE - In hydrogen generating apparatus, hydrogen is generated from ammonia with a simple configuration, and further the oxidation reaction and/or the decomposition reaction of ammonia is effectively accelerated with a reduced amount of a relatively expensive noble metal catalyst used in the ammonia oxidation part and/or the ammonia decomposition part.    DETAILED DESCRIPTION - A hydrogen generating apparatus for generating hydrogen from ammonia, comprises an ammonia oxidation part (10) having an ammonia oxidation catalyst (11a, 11b) which oxidizes ammonia, and an ammonia decomposition part (20) having an ammonia decomposition catalyst (21) which decomposes ammonia to generate nitrogen and hydrogen; where the ammonia decomposition part is located downstream of the ammonia oxidation part in a direction of feed gas flow; and where the hydrogen generating apparatus satisfies either or both of the following conditions (i) and (ii): (i) the ammonia oxidation catalyst contains both a noble metal catalyst and a base metal catalyst, and a loading concentration of the noble metal catalyst in an upstream portion of the ammonia oxidation part in the direction of feed gas flow is higher than a loading concentration of the noble metal catalyst in a downstream portion of the ammonia oxidation part in the direction of feed gas flow, (ii) the ammonia decomposition catalyst contains both a noble metal catalyst and a base metal catalyst, and a loading concentration of the noble metal catalyst in a downstream portion of the ammonia decomposition part in the direction of feed gas flow is higher than a loading concentration of the noble metal catalyst in an upstream portion of the ammonia decomposition part in the direction of feed gas flow.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of hydrogen generating apparatus.    Ammonia oxidation part (10)    Ammonia oxidation catalyst (11a, 11b)    Ammonia decomposition part (20)    Ammonia decomposition catalyst (21)    Hydrogen generating apparatus (51)