Part of an electrode, specifically a current collector and an active material layer, for a secondary battery is subjected to cutting processing to have a complex shape. For example, a stack of the first current collector and the first active material layer has a first slit and a second slit. Each of the first slit and the second slit passing across the first current collector and the first active material layer and extending from an edge of the first current collector. Another stack of the second current collector and the second active material layer has a third slit and a fourth slit. Each of the third slit and the fourth slit passing across the second current collector and the second active material layer and extending from an edge of the second current collector.