To improve the efficiency of a phosphoric acid type fuel cell, by making a flat surface-like sheet, formed by carbonizing hollow strings to align them in parallel, an electrode.

This electrode has the following constitution: (a) a hollow string coat, equipped with well known fine holes as a separation coat, is made into a carbon fiber, to align these carbonized hollow strings 1 in parallel to constitute a flat surface-like sheet 2; (b) platina fine wires are passed through several places in the hollow strings to be bound so that the hollow strings, made into a carbon fiber, can not be isolated with each other; (c) the cross sections of the flat surface-like sheets of the carbonized hollow strings, in both the upper and lower parts; are made the aggregate of the semicircular hollow strings.