A cylindrical lithium secondary battery that is excellent in resistance to short-circuits, is capable of preventing a capacity loss due to dropping, and has a good balance in battery characteristics. The cylindrical lithium secondary battery includes: a cylindrical battery can; an electrode assembly; and a non-aqueous electrolyte. The electrode assembly has a porous heat-resistant layer that is interposed between the positive electrode and the negative electrode. The electrode assembly has a central cavity into which a hollow mandrel is inserted. The hollow mandrel has a slit that extends along the entire length thereof. The outer diameter A of the hollow mandrel and the width B of the slit satisfy the relation: 0.1≦B/A≦0.6.