ELECTROCHEMICAL CELL

An electrochemical cell includes a cell stack including a plurality of unit cells stacked on one another and each being a plate and including an electricity generator and a casing accommodating the electricity generator, and an outer case accommodating the cell stack. The outer case includes at least one rib in a surface area between an outer edge of the outer case and an outer periphery of the cell stack as viewed in a stacking direction of the cell stack. The at least one rib is a portion of the surface area protruding outward.