The invention discloses a battery cell comprising a wrinkle preventing member. The present invention provides a battery cell having: an electrode assembly which comprises a laminated structure of positive electrodes, negative electrodes and separators interposed therebetween, and which is equipped in a cell case while being impregnated with an electrolyte solution; the electrode assembly and the cell case in which each has transformability and can be transformed in correspondence with the shape of a device on which a battery cell is mounted; and a wrinkle preventing member, for preventing wrinkles if the cell case is transformed, added on one or more parts of the inner sides of the cell case facing the outermost electrodes of the electrode assembly or on one or more parts of the outer sides of the electrode assembly.