PROBLEM TO BE SOLVED: To more enhance the working efficiency of a cell corresponding to gas per unit volume flowing through a gas passage in a honeycomb-shaped electrochemical cell. SOLUTION: This electrochemical cell 1 is equipped with airtight solid electrolyte materials 4A, 4B; a plurality of first gas passages 5A, 5B; a plurality of second gas passages 6A, 6B; and first electrodes 9 facing the first gas passages and second electrodes facing the second gas passages. The first electrodes 9 and the second electrodes 8 are installed so as to interpose the solid electrolyte materials 4A, 4B respectively. The areas of the first gas passages 5A, 5B as viewed by cutting the electrochemical cell in the cross section direction is smaller than the second gas passages 6A, 6B.