HYDROGEN GENERATOR

Disclosed is a hydrogen generator that prevents the reformate water from bypassing the evaporator in a hydrogen generator, and the occurrence of sudden temperature changes within an evaporation flow path. The hydrogen generator comprises: an evaporator that produces a mixed gas by mixing a raw material gas containing methane with water vapor; a reformer that changes the mixed gas into a hydrogen-containing gas through a steam reforming reaction; and a combustor that supplies heat to the evaporator and the reformer. The evaporator comprises: an inner cylinder; an outer cylinder enclosing the inner cylinder; and a middle cylinder that is inserted between the inner cylinder and the outer cylinder, and that defines a helical flow path between the inner cylinder and the outer cylinder, through which water supplied from the outside flows. On the inner peripheral surface and the outer peripheral surface of the middle cylinder, helical projections and recesses are integrally formed at the front and back, the top surface of the projections on the inner peripheral surface of the middle cylinder come into contact with the outer peripheral surface of the inner cylinder, and the top surface of the projections on the outer peripheral surface of the middle cylinder come into contact with the inner peripheral surface of the outer cylinder.