The present invention provides a lithium secondary battery using a lithium transition metal composite oxide as a positive electrode active material. The lithium secondary battery is constituted with a negative electrode on and/or around which a cyclic silazane-based compound and/or a reaction product thereof are present. The cyclic silazane-based compound comprises a Si—N bond in the ring constituting the cyclic silazane-based compound and also has at least one vinyl group.