A lithium-containing complex transition metal oxide forming the positive electrode active material of a non-aqueous electrolyte secondary cell in one embodiment is a secondary particle obtained by aggregating primary particles. Ion chromatography analysis of a sample obtained by adding the positive electrode active material to an alkali solution and absorbing a distillate thereof in sulfuric acid results in detection of 2-200 pm of ammonia relative to the mass of the positive electrode active material. When a filtrate of an aqueous dispersion in which 1 g of the positive electrode active material is dispersed in 70 ml of pure water is titrated with hydrochloric acid, the value of Y−X is 50-300 mol/g and the value of X−(Y−X) is no higher than 150 mol/g, with X mol/g being the acid consumption until a first inflection point on the pH curve and Y mol/g being the acid consumption until a second inflection point.