A manufacturing method includes providing a cell stack including fuel cells and has a first end and a second end. A first end plate is provided at the first end of the cell stack. The first end plate has a first end plate through hole. A second end plate is provided at the second end of the cell stack. A connecting member is provided to connect the first end plate and the second end plate. A first knock is inserted into the first end plate through hole and into a first connecting member installing hole. A first seal is located between the first knock and the first end plate in the first end plate through hole. The first end plate is moved in the stacking direction to contact the connecting member. A fastening member is inserted into the first knock.