This invention prevents reduction of hydrogen permeability and deterioration in hydrogen separation members that use an oxygen-containing gas as a cathode off gas and a purge gas. Described is a hydrogen separation device that includes a reformed gas passage, a purge gas passage, and a hydrogen separation membrane. A supply of reformed gas flows through the reformed gas passage. A cathode off gas discharged from a fuel cell cathode flows through the purge gas passage to carry hydrogen transmitted through the hydrogen separation membrane to a fuel cell anode. A portion of the hydrogen separation membrane near the supply of the cathode off gas has enhanced heat resistance that prevents deterioration of the hydrogen separation membrane even when hydrogen transmitted through the membrane reacts with oxygen remaining in the cathode off gas to raise the temperature in the vicinity of the portion close to the supply of the cathode off gas.