SECONDARY BATTERY

A secondary battery includes an electrode assembly including a first electrode, a second electrode, and a separator, a case body accepting the electrode assembly through one opened side surface and including a first binding surface formed along a circumference of the one opened side surface, and a case cover bound to the one opened side surface of the case body and including a second binding surface formed along a circumference of the case cover such that the second binding surface is able to tightly bind to the first binding surface. At least a part of the first binding surface and the second binding surface are inclined.