Provided is a hydrogen generating apparatus adaptable to fluctuating hydrogen demand, particularly by enabling large-scale hydrogen production, generating pure hydrogen at a high yield. The hydrogen generating apparatus 1 generates hydrogen gas from a source gas by decomposing the source gas through catalysis and transforming it into plasma through electric discharge. The hydrogen generating apparatus 1 includes a dielectric body 2 defining a source gas flow channel 13, a catalyst 10 that decomposes at least part of the source gas in the source gas flow channel 13 to generate hydrogen gas, an electrode 3 contacting the dielectric body 2, a hydrogen separation membrane 5 facing the electrode 3 across the dielectric body 2, a hydrogen flow channel 18 guiding hydrogen separated by the hydrogen separation membrane 5, and a high-voltage power supply 6 supplying power to cause electric discharge between the hydrogen separation membrane 5 and the electrode 3.