Palladium membranes are permeable only to hydrogen. Producing high purity hydrogen by means of such membranes and feeding it to fuel cells as fuel, the energy efficiency of fuel cells can be improved. However, palladium is extremely expansive. We have, therefore, looked for new membrane materials to find that amorphous Zr₃₆Ni₆₄ alloy membranes have a practical level of hydrogen permeability and good mechanical properties even in a hydrogen atmosphere. Moreover, we have developed various amorphous alloy membranes including amorphous Zr₆₀Ni₈Al₁₅Cu₁₅Co₂ with a high permeability comparable to palladium. Since 2003, we have been developing a prototype of hydrogen production system using amorphous alloy membranes in METI’s regional consortium project. We have already succeeded to produce amorphous alloy membranes as wide as 50 mm, using which we have successfully demonstrated hydrogen separation from gas mixture containing carbon monoxide and carbon dioxide.