A portable fuel cell stack is provided in which the number of components is reduced by reducing the number of flow field plates, cell performance is improved by reducing the number of contact portions to thereby lower internal resistance, and fuel is supplied from the center of an end plate directly to a fuel distribution manifold. The portable fuel cell stack includes two end plates, a plurality of unit cells positioned between the two end plates, a fuel distribution manifold positioned in the center of the unit cell for fuel supply thereto, a tie bolt passed through the centers of the fuel manifold and the unit cell for integration of these members, and fixing nuts threaded to both ends of the tie bolt for integrally clamping the plurality of unit cells together between the end plates via an O-ring, etc. The unit cell includes a polymer electrolyte membrane, an oxygen electrode and a fuel electrode installed on both sides of the polymer electrolyte membrane, a flow field plate adjacent to the oxygen electrode side, and a separator plate on the outside of the flow field plate adjacent in contact therewith and another separator plate on the outside of the fuel electrode side in contact therewith. One of the fixing nuts has a fuel supply port connecting to the fuel distribution manifold.