A battery of the present disclosure includes a power generation element. Each of the plurality of unit cells includes an electrode layer, a counter electrode layer, and a solid electrolyte layer arranged between the electrode layer and the counter electrode layer. The power generation element includes a first principal, a second principal opposite to the first principal, and a side surface connecting the first principal and the second principal. The side surface includes: a first inclined surface that connects to the first principal and forms an obtuse angle with the first principal; and a second inclined surface that connects to the second principal and forms an obtuse angle with the second principal. At least one of the first inclined surface and the second inclined surface is provided across two or more of the plurality of unit cells.