NOVELTY - Non-aqueous electrolyte secondary battery comprises: electrode body comprising (a1) positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on a surface of a positive electrode current collector, (a2) negative electrode, and (a3) separator placed between positive and negative electrodes; non-aqueous electrolyte; and casing that accommodates electrode body and non-aqueous electrolyte. In the battery, at least part of surface of the positive electrode active material is coated with surface treatment layer.    USE - The battery is useful for driving power supplies of: mobile information terminals comprising cellular phones, notebook computers, and personal digital assistants; and high-power machines comprising electric vehicles and power tools.    ADVANTAGE - The battery: achieves high reliability having high capacity; and increases storage characteristics at high temperature without impairing the load characteristics, in the case where the charge cut-off voltage is increased to achieve high battery capacity.    DETAILED DESCRIPTION - Non-aqueous electrolyte secondary battery comprises: an electrode body comprising (a1) a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on a surface of a positive electrode current collector, (a2) a negative electrode, and (a3) a separator placed between the positive electrode and the negative electrode; a non-aqueous electrolyte; and a casing that accommodates the electrode body and the non-aqueous electrolyte. In the battery, at least part of a surface of the positive electrode active material is coated with a surface treatment layer comprising a phosphate compound that contains at least one element comprising neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium. An INDEPENDENT CLAIM is also included for producing the non-aqueous electrolyte secondary battery comprising: coating at least part of a surface of a positive electrode active material with a surface treatment layer comprising a phosphate compound by adding a phosphate and a salt containing at least one of the elements to a solution containing the positive electrode active material; preparing a positive electrode by forming a positive electrode active material layer on a surface of a positive electrode current collector, where the positive electrode active material layer contains a positive electrode active material that is coated with the surface treatment layer comprising the phosphate compound; preparing an electrode body by placing a separator between positive and negative electrodes; and placing the electrode body and a non-aqueous electrolyte in a casing.