A fuel cell comprising: a plurality of stacked cell units , each cell unit comprising at least: an electrically conductive interconnector having a front surface and a back surface; a first connection member which is electrically connected to the interconnector and contacts the back surface of the electrically conductive interconnector ; a single cell which includes an anode , an electrolyte , and a cathode , and which is electrically connected to the first connection member ; a separator having an opening which is connected to an outer peripheral portion of the single cell ; and a second connection member which is electrically connected to the front surface of an electrically conductive interconnector of an adjacent cell unit of the stacked cell units ; wherein the cell units being clamped together in a stacking direction, the fuel cell being characterized in that at least one single cell within single cells of a plurality of stacked cell units has a thickness different from the other single cells , wherein for the single cell having a thickness different from a thickness of the other single cells a relation of 0 ≤ (D2 - D1) ≤ 200 μm is fulfilled, wherein D2 is the sum of the thickness of the connection members and single cell , and wherein D1 is the distance between the respective back surface of the electrically conductive interconnector and the front surface of an electrically conductive interconnector of the respective adjacent cell unit , by using a selected respective connection member having a predetermined thickness before the assembly of the fuel cell , which connection member is selected from among connection members having different thicknesses, such that the relation of 0 ≤ (D2 - D1) ≤ 200 μm is fulfilled. an electrically conductive interconnector having a front surface and a back surface; a first connection member which is electrically connected to the interconnector and contacts the back surface of the electrically conductive interconnector ; a single cell which includes an anode , an electrolyte , and a cathode , and which is electrically connected to the first connection member ; a separator having an opening which is connected to an outer peripheral portion of the single cell ; and a second connection member which is electrically connected to the front surface of an electrically conductive interconnector of an adjacent cell unit of the stacked cell units ; wherein the cell units being clamped together in a stacking direction, the fuel cell being characterized in that at least one single cell within single cells of a plurality of stacked cell units has a thickness different from the other single cells , wherein for the single cell having a thickness different from a thickness of the other single cells a relation of 0 ≤ (D2 - D1) ≤ 200 μm is fulfilled, wherein D2 is the sum of the thickness of the connection members and single cell , and wherein D1 is the distance between the respective back surface of the electrically conductive interconnector and the front surface of an electrically conductive interconnector of the respective adjacent cell unit , by using a selected respective connection member having a predetermined thickness before the assembly of the fuel cell , which connection member is selected from among connection members having different thicknesses, such that the relation of 0 ≤ (D2 - D1) ≤ 200 μm is fulfilled. <EOS>