A flexible battery is provided. A flexible battery according to an embodiment of the present invention comprises: an electrode assembly; an exterior material for sealing the electrode assembly together with an electrolyte; and a plurality of patterns having ridge portions and groove portions repeatedly formed along the lengthwise direction, wherein the maximum bending curvature at which the battery can be bent through the plurality of patterns is adjusted through the gap (L) between two neighboring patterns and the depth (d) of the patterns.