The disclosure relates to a secondary battery including: a cap assembly including a cap plate including an electrode lead-out hole and an electrode terminal disposed on the cap plate; a current collector including a main body located at a side of the cap plate and an extending portion extending toward the electrode terminal, where the extending portion includes a top plate connected to the electrode terminal and a side plate connected to the main body, and the side plate and the top plate are configured to form a recess; and an insulating protection component including a column portion disposed in the recess, where surfaces of the side plate and the top plate which form the recess are in contact with the column portion and covered by the column portion.