Cell unit

A cell unit CU includes a cell structure 1, a metal support plate 2 disposed on one side surface of the cell structure 1, and a frame 3 holding an outer peripheral part of the support plate 2. The cell structure 1 has a lamination of an anode electrode layer 4, an electrolyte layer 5, and a cathode electrode layer 6, in this order. The frame 3 includes a displacement guide 7 at least on one side surface of the frame 3. The displacement guide 7 has a coefficient of thermal expansion that is different from that of the frame 3 and is configured to make the frame 3 curve so that the cell structure 1 is concaved in accompany with thermal expansion. In the cell unit CU, a risk of concentration of tensile stress on the electrolyte layer 5 at the time of thermal expansion during operation is removed without reducing the strength of the frame 3, whereby occurrence of a crack and the like in the electrolyte layer 5 can be prevented beforehand.