A non-aqueous electrolyte secondary battery comprises a negative electrode having an active material comprised of lithium or a material capable of absorbing and releasing lithium, a lithium ion conductive non-aqueous electrolyte, and a positive electrode. The positive electrode active material is comprised of a composite represented by composition formula Li.sub.a R.sub.b L.sub.c M.sub.d O.sub.2 where R is one or more metalloid elements selected from boron B and silicon Si, L is at least one element selected from metals and metalloids of Groups IIIA and IVA of the periodic table, alkaline earth metals, and metals selected from the group consisting of Ti, Mn, Cu and Zn, M represents transition metal elements comprising at least Ni and Co, R, L and M are different, and a, b, c and d satisfy 0