A separator for fuel cells is provided, which has excellent electrical conductivity, mechanical strength and gas impermeability. The separator is a molded article of a carbon-phenol resin molding compound obtained by reacting a phenol with an aldehyde in the presence of a catalyst, while mixing them with a carbon powder. As the catalyst, it is possible to use at least one selected from tertiary amines, carbonates, hydroxides and oxides of alkali metals or alkali earth metals. It is preferred that a content of nitrogen constituent in the molding compound is 0.3 wt % or less, and a carbon content in the molding compound is within a range of 75 wt % to 97 wt %.