Disclosed is a molten carbonate fuel cell comprising an electrolyte body sandwiched between a pair of electrodes, outflow of an electrolyte from the electrolyte body being diminished to suppress an increase of the internal resistance and occurrence of a gas crossover, which accompany the outflow of the electrolyte, so as to increase the life time of the fuel cell. The molten carbonate fuel cell of the present invention comprises a pair of conductive electrodes, an electrolyte body sandwiched between the pair of electrodes and including a porous body containing a retaining material and a reinforcing material and an electrolyte impregnated in the porous body and containing an alkali carbonate mixture, the retaining material containing fine particles having an average particle diameter of 0.2 to 0.6 .mu.m and the reinforcing material containing short fibers having a diameter of 0.5 to 5 .mu.m and a length of at most 50 .mu.m, fuel gas supplying means for supplying a fuel gas to one of the pair of electrodes, and oxidant gas supplying means for supplying an oxidant gas to the other of the pair of electrodes.