A secondary battery includes an electrode assembly, which has improved safety by reducing a density of an active material centrally positioned in the electrode assembly. In the secondary battery, an electrode assembly includes a first electrode plate, a second electrode plate and a separator between the first electrode plate and the second electrode plate, the first electrode plate including a first electrode current collector and a first active material layer on the first electrode current collector, the first active material layer including a first active material, a binder and a conductive agent, and a portion of the first active material layer at a central portion of the electrode assembly including the first active material at a lower density than a density of the first active material at a portion of the first active material layer at a peripheral portion of the electrode assembly.