A secondary battery including: a battery unit including a battery cell and a lead tab that protrudes from the battery cell; a frame case for supporting the battery unit and including a first support portion for supporting the battery cell and a second support portion for supporting the lead tab; and a connection member for perforating a connection hole formed in the lead tab and extending in a direction of the second support unit, wherein the connection hole of the lead tab includes: a first connection hole that is spaced apart from a first edge of the lead tab by a first width; and a second connection hole that is spaced apart from a second edge of the lead tab by a second width. The secondary battery may reduce electrical resistance of a charge/discharge path and has improved efficiency.