This lithium secondary battery is a lithium secondary battery that employs a lithium transition metal composite oxide as a positive-electrode active material. A cyclic silazane compound and/or a reaction product thereof exist(s) in the vicinity of the negative electrode that constitutes this lithium secondary battery. The cyclic silazane compound includes a Si-N bond in a ring that constitutes the cyclic silazane compound, and the cyclic silazane compound includes at least one vinyl group.