Lithium secondary battery

A lithium secondary battery comprising: a battery case, and an internal electrode body contained in the battery case and including a positive electrode, a negative electrode and a separator made of porous polymer, the positive electrode and the negative electrode being wound or laminated through the separator so that the positive electrode and the negative electrode are not brought into direct contact with each other. The battery case has a form of a cylindrical container opened at both ends or a bottomed cylindrical container opened at only one end and is composed of pure aluminum or aluminum alloy in which one or more components selected from manganese, magnesium, silicon and copper is added in aluminum, wherein a relationship of 0.004 ≤ t/d ≤ 0.04 is established where said battery case is cylindrical, its outer diameter is d, and its wall thickness is t.