Abstract: In a multiphase hydrogen permeation alloy comprising a phase in charge of hydrogen permeation and a phase in charge of hydrogen embrittlement resistance, a structure in which the phase in charge of hydrogen permeability is continuously interconnected and in which more preferably the growth direction of the aforementioned phase in charge of hydrogen permeation lies aligned in the thickness direction of the permeation membrane. As the hydrogen permeation alloy, an Nb—Ti—Co alloy is exemplified, wherein the phase in charge of hydrogen permeability is made of an (Nb, Ti) phase and the aforementioned phase in charge of hydrogen embrittlement resistance is made of a CoTi phase. By virtue of the fact that the growth direction of the phase in charge of hydrogen permeation lies aligned in the thickness direction of the permeation membrane, the hydrogen permeation pass length becomes short to give further improved hydrogen permeation property.