Disclosed is a self-regulating hydrogen gas generator for a hydrogen fuel cell. The self-regulating hydrogen gas generator includes a fuel tank, defining an inner space having a designated volume, provided with a hydrogen outlet communicating the inner space, a fuel solution, containing a hydrogen storing material, stored in the fuel tank, and a catalyst contacting the fuel solution for generating hydrogen gas, wherein the catalyst fills a catalytic reactor, provided with a closed portion for interrupting the contact between the catalyst and the fuel solution, and an opened portion contacting the fuel solution, so that the generation and interruption of hydrogen gas are actively regulated based on the increase and decrease of the pressure of the fuel tank.