HYDROGEN GENERATOR

Provided is a hydrogen generator which is suppressed in temperature unevenness in a reforming region and has improved thermal efficiency, while having good maintenance properties. A hydrogen generatoraccording to the present invention is provided with: a reforming catalyst which causes a reforming reaction of a hydrocarbon-based gas with water vapor, thereby reforming the hydrocarbon-based gas into a hydrogen-rich reformed gas; a reformer 10 which is filled with the reforming catalyst, and in which the reforming reaction is carried out; and a combustion chamber 20 in which a fuel gas is combusted, thereby obtaining a reaction heat that is to be applied to the reforming reaction. At least a reforming region where the reforming reaction is carried out in the reformer 10 is arranged inside the combustion chamber 20; and a water vapor generator 30 which generates water vapor that is to be introduced into the reformer 10 is arranged outside the combustion chamber 20. Consequently, it is not necessary for the combu