A fuel-cell-stack manufacturing method, includes arranging an extension portion extended from a proximal end of a raised piece on one surface of a base material disposed so as to abut at least one of a cathode side separator and the anode side separator, and setting an interval between the anode side separator and the cathode side separator along a lamination direction so that deformation of the raised piece exceeds an elastic deformation region and enters a plastic deformation region, and is also in a region in which the proximal end moved due to the deformation does not come in contact with the cathode side separator or the anode side separator.