Disclosed is a secondary battery including a plurality of electrode assemblies. The secondary battery includes a first electrode assembly including a first cathode, a first separator and a first anode, and a second electrode assembly including a second cathode, a second separator and a second anode, wherein, when an electrode plate area of the second electrode assembly is smaller than that of the first electrode assembly, a cross-sectional thickness of the second electrode assembly is larger than that of the first electrode assembly.