A high temperature fuel cell (HTFC) which uses a hydrogen gas fuel such as a hydrogen gas at a high temperature is one of new energy devices. Compared to a thermal power generation system, a solid oxide fuel cell which can use the same amount of a fuel at a low temperature without a reformer can suppress heat loss during operation. Therefore, it is possible to increase the thermal efficiency. Since hydrogen is used as a fuel, it is possible to expect the fuel cell to be used for cleanly providing electric power which does not generate any CO2. The high temperature fuel cell includes a solid electrolyte layer formed of an oxide ion conductor. This solid electrolyte layer is disposed between an air electrode (cathode) and a fuel electrode (anode) (for example, see Patent Literatures 1 and 2). The air electrode includes a porous electrode layer which has, on the inner surface thereof, an electrode catalyst layer which promotes an electrochemical reaction between the air and the oxygen. The fuel electrode includes a porous electrode layer which has, on the inner surface thereof, an electrode catalyst layer which promotes an electrochemical reaction between the fuel and the oxygen. A solid electrolyte layer is provided between the air electrode and the fuel electrode. In the solid electrolyte layer, oxygen is ionized, and then, moves to an air electrode side while electrons are generated, and it is possible to obtain an electromotive force. On the other hand, hydrogen ionized in the fuel electrode moves toward the air electrode, and thus, water is generated by the reaction of water vapor. A fuel cell system is provided by stacking power generating elements each including a solid electrolyte layer and a fuel electrode and an air electrode on both sides of a support substrate such as a metal plate. A plurality of fuel cells are stacked in series. In such a fuel cell system, gas leakage (a leak) may occur from a plurality of holes (joints) which connect the air electrodes of the adjacent fuel cells with each other. In order to suppress the occurrence of a leak, a technology of sealing each joint has been suggested (for example, Patent Literature 3). For example, the technology disclosed in Patent Literature 3 is a fuel cell stack system including a stacked cell body which includes a cell stack having a plurality of stacked fuel cells, an upper manifold which supplies a fuel gas (a fuel gas containing hydrogen) to the stacked cell body, and a lower manifold which collects an oxidizing gas (an oxidizing gas containing oxygen) discharged from the stacked cell body. The lower manifold is connected to the fuel cell stack. A plurality of joint channels each having a through hole are formed in the stacked cell body. The through hole is aligned with the upper side manifold. A plurality of seals are disposed on the lower side (a first side which is provided by the fuel cell stack) of the lower manifold such that an outer peripheral portion of each seal abuts against the outer peripheral side of the lower manifold. Each seal is fixed to the lower manifold by inserting a fixing member into the through hole formed in the seal. Each seal includes a protrusion formed to abut against the lower manifold. Each seal includes a thin plate portion and a support portion which supports the thin plate portion. The support portion includes an opening through which the fixing member can be inserted. The support portion includes an anchor. An inner peripheral portion of the opening is formed to bulge toward the outside. The fixing member is inserted into the through hole formed in the seal and into the opening formed in the support portion, so that the protrusion provided on the seal abuts against the lower manifold. Thus, the support portion supports the thin plate portion such that the thin plate portion is inclined to be positioned in the lower side (the lower side of the seal) with respect to the outer peripheral side of the lower manifold. Accordingly, when the lower manifold deforms, for example, due to a load when stacking the fuel cells, the thin plate portion provided by the seal is elastically deformed so that the inner peripheral portion of the through hole formed in the thin plate portion bulges toward the outside. When the outer peripheral portion of the lower manifold comes in contact with the thin plate portion, the outer peripheral portion of the lower manifold is elastically deformed so that it bulges toward the outside, with the result that the outer peripheral portion comes into contact with the protrusion provided on the seal. Therefore, even when the outer peripheral portion of the lower manifold comes into contact with the protrusion, a reaction force (a reactive force) is applied to the protrusion such that the reaction force supports the lower manifold, so that it is possible to prevent or suppress the occurrence of a leak. [Patent Literature 1] JP-A-2008-224780 [Patent Literature 2] JP-A-2005-172909 [Patent Literature 3] JP-A-2007-295949