A rechargeable battery, comprising: an electrode assembly including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate; a can having a first side surface (120s1), a second side surface (120s2), a third side surface (120s3), a fourth side surface (120s4) and an opening at one side thereof through which the electrode assembly is inserted, the electrode assembly being accommodated in the inside of the can; and a cap plate that seals the opening of the can such that an opened upper surface of the can is closed by the cap plate, the cap plate having a thickness in a thickness direction (z), wherein the first side surface (120s1) and the second side surface (120s2) extend in the thickness direction (z) of the cap plate from a longer side portion (130e1, 130e2) of the cap plate, the first side surface (120s1) and the second side surface (120s2) facing in opposite directions from each other, and wherein the third side surface (120s3) and the fourth side surface (120s4) extend along the thickness direction (z) of the cap plate from a shorter side portion (130e3, 130e4) of the cap plate, the third side surface (130e3) and the fourth side surface (130e4) facing in opposite directions from each other, the can including: a first vent on one side of a first side surface (120s1) of the can, the one side being closer to the third side surface (120s3) than to the fourth side surface (120s4); and a second vent on one side of a second side surface (120s2) of the can, the one side being closer to the fourth side surface (120s4) than to the third side surface (120s3) wherein the first side surface (120s1) of the can and the second side surface (120s2) of the can are located on opposite sides of the rechargeable battery from each other; the first vent and the second vent are each in a form of a recess, and; the first vent extends parallel to the thickness direction (z) of the cap plate or extends along a perpendicular direction (x) with respect to the thickness direction (z) of the cap plate, and the second vent extends along an oblique direction with respect to the thickness direction (z) of the cap plate, characterized in that the depth d1 of the first vent is formed deeper than the depth d2 of the second vent and d1 represents the depth of the first vent and d2 represents the depth of the second vent, and that the first vent is on one side of the lower portion of the first side surface (120s1), and the second vent is on one side of the upper portion of the second side surface (120s2). an electrode assembly including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate; a can having a first side surface (120s1), a second side surface (120s2), a third side surface (120s3), a fourth side surface (120s4) and an opening at one side thereof through which the electrode assembly is inserted, the electrode assembly being accommodated in the inside of the can; and a cap plate that seals the opening of the can such that an opened upper surface of the can is closed by the cap plate, the cap plate having a thickness in a thickness direction (z), wherein the first side surface (120s1) and the second side surface (120s2) extend in the thickness direction (z) of the cap plate from a longer side portion (130e1, 130e2) of the cap plate, the first side surface (120s1) and the second side surface (120s2) facing in opposite directions from each other, and wherein the third side surface (120s3) and the fourth side surface (120s4) extend along the thickness direction (z) of the cap plate from a shorter side portion (130e3, 130e4) of the cap plate, the third side surface (130e3) and the fourth side surface (130e4) facing in opposite directions from each other, the can including: a first vent on one side of a first side surface (120s1) of the can, the one side being closer to the third side surface (120s3) than to the fourth side surface (120s4); and a second vent on one side of a second side surface (120s2) of the can, the one side being closer to the fourth side surface (120s4) than to the third side surface (120s3) a first vent on one side of a first side surface (120s1) of the can, the one side being closer to the third side surface (120s3) than to the fourth side surface (120s4); and a second vent on one side of a second side surface (120s2) of the can, the one side being closer to the fourth side surface (120s4) than to the third side surface (120s3) wherein the first side surface (120s1) of the can and the second side surface (120s2) of the can are located on opposite sides of the rechargeable battery from each other; the first vent and the second vent are each in a form of a recess, and; the first vent extends parallel to the thickness direction (z) of the cap plate or extends along a perpendicular direction (x) with respect to the thickness direction (z) of the cap plate, and the second vent extends along an oblique direction with respect to the thickness direction (z) of the cap plate, characterized in that the depth d1 of the first vent is formed deeper than the depth d2 of the second vent and d1 represents the depth of the first vent and d2 represents the depth of the second vent, and that the first vent is on one side of the lower portion of the first side surface (120s1), and the second vent is on one side of the upper portion of the second side surface (120s2).