A hydrogen separator comprising a porous substrate composed mainly of a ceramic having a large number of pores connecting from one surface of the substrate to other surface, and a hydrogen-separating layer made of a hydrogen permselective metal formed on the porous substrate via an intermediate layer made of an electron-conductive ceramic. The hydrogen separator hardly generates defects such as peeling, cracks or the like in the hydrogen-separating layer and is suitable for use even when the hydrogen separator is exposed to a heat cycle, used under high temperature conditions or/and used for long-term.