ELECTROCHEMICAL CELL

An electrochemical cell includes a first unit cell including a first power generation element and a first inner container which accommodates the first power generation element; a second unit cell including a second power generation element and a second inner container which accommodates the second power generation element; an outer container which accommodates the first unit cell and the second unit cell. A surface of the first inner container is provided with a convexity that has a curved surface and/or a flat surface, and a surface of the second inner container is provided with a concavity that has a curved surface and/or a flat surface. The electrochemical cell includes a fit portion in which the convexity is fitted in the concavity.