Provided is a lithium secondary battery using a positive electrode active material which operates at a charging voltage in a region exceeding 4.3 V, and a novel positive electrode active material for a lithium secondary battery which can further enhance the output characteristics. Proposed is a positive electrode active material for a lithium secondary battery including positive electrode active material particles obtained by equipping the entire surface or a part of the surface of lithium manganese-containing composite oxide particles (also referred to as the “core particles”) operating at a charging voltage in a region exceeding 4.3 V in a metal Li reference potential with a layer A containing at least Ti, Al, Zr, or two or more kinds of these, and C.