PURPOSE: To simplify manufacturing of the said gas separator and prevent generation of its deformation by fitting a carbon paper laminating body to which water repellent treatment is applied on both the front and rear of a carbon substrate.

CONSTITUTION: A substrate 4 is formed by mixing resin powder in graphite powder, pressure-heating-molding them, and providing opposed side edges 2 and 3 on both the flat front and rear in the mutually crossed direction. Simultaneously porous gas passages 6 and 7 are formed by fitting the laminating body of carbon paper 5 that is immersed in a fluororesin dispersion, withdrawn, and heat-treated at the bonding temperature of the fluororesin between the side edges 2 and 3. Besides, a cell pile is formed by laminating with an electrolytic matrix and a unit cell consisting of positive and negative electrodes. As a result, manufacturing of the said gas separator can exceedingly be simplified by using the carbon paper laminating body 5 instead of a number of gas supply grooves.