Conventionally known examples of this type of cells include a cell formed of an oblong power generating element that is made by: forming a cylindrical core; winding sheet-shaped positive and negative electrodes around the core with sheet-shaped separators disposed between the positive and negative electrodes, thereby fabricating a cylindrical power generating element; and then pressing the cylindrical power generating element radially inward from both sides into an oblong shape (cf., Patent Document 1).