A secondary battery comprises a pair of collectors made of a valve action metal, a pair of electrodes comprising a sulfuric acid aqueous solution, a separator and an outer can. Each collector is covered with an oxide film of a thickness of 1.7-10 nm. The oxide film is formed in a range of from 30% by area or more to less than 100% by area relative to the surface area of the collector. Each collector has one electrode disposed thereon.