A secondary battery includes an electrode assembly comprising a first electrode plate, a second electrode plate and a separator located between the first electrode plate and the second electrode plate; a case accommodating the electrode assembly; a cap plate sealing the case; a first collector plate comprising a first vertical part electrically connected to the first electrode plate, a first horizontal part bent from the first vertical part and extending between the electrode assembly and the cap plate, and a first protrusion protruding from the first horizontal part; and a first electrode terminal electrically connected to the first collector plate and extending through the cap plate, wherein the first electrode terminal has a coupling opening engaged with the first protrusion.