A secondary battery includes an electrode body including a positive electrode plate and a negative electrode plate; a battery case containing the electrode body; a positive electrode terminal attached to the battery case; a conductive member having an opening adjacent to the electrode body; a deformation plate that seals the opening, and a current collector. The positive electrode plate and the positive electrode terminal are electrically connected to each other via a first positive electrode current collector, the deformation plate, and the conductive member. The deformation plate has a thick portion, which has a larger thickness than the surrounding area, in a central part. The thick portion of the deformation plate is welded to the first positive electrode current collector to form a weld.