A method of manufacturing a non-aqueous electrolyte secondary battery is provided wherein the positive electrode is made from a lithium-metal composite oxide represented by the general formula Li.sub.x(Ni.sub.1-y, Co.sub.y).sub.1-zM.sub.zO.sub.2 (0.98.ltoreq.x.ltoreq.1.10, 0.05.ltoreq.y.ltoreq.0.4, 0.01.ltoreq.z.ltoreq.0.2, in which M represents at least one element selected from the group consisting of Al, Mg, Mn, Ti, Fe, Cu, Zn and Ga), and having an average particle diameter of 5 .mu.m to 10 .mu.m a C-amount of 0.14 wt % or less measured by way of the high-frequency heating-IR absorption method, and a Karl Fischer moisture content of 0.2 wt % or less when heated to 180.degree. C. and the method comprising the steps of applying a paste of active material for positive electrode to electrode plate to make an electrode, then drying the electrode, and pressing and then installing the electrode in a battery, in a work atmosphere having an absolute moisture content of 10 g/m.sup.3 or less.