A lithium-ion secondary battery (100) includes a wound electrode body (80), a nonaqueous electrolyte, and a box-shaped case (50). The wound electrode body includes a positive electrode (10), a negative electrode (20), and a separator (40). The box-shaped case contains the wound electrode body and the nonaqueous electrolyte. The wound electrode body includes a starting-end-side negative electrode remainder portion (22) provided in a winding-direction starting end portion (81) of the wound electrode body. The winding-direction starting end portion exists at a winding center side. The starting-end-side negative electrode remainder portion protrudes toward the winding center side along a winding direction beyond the positive electrode. A surplus nonaqueous electrolyte exists in a gap between the wound electrode body and the box-shaped case. The starting-end-side negative electrode remainder portion is positioned in a region where the surplus nonaqueous electrolyte exists, when the lithium-ion secondary battery is disposed in a predetermined posture.