Storage performance in a charged state is improved with a non-aqueous electrolyte secondary battery using gamma-butyrolactone as a solvent. A non-aqueous electrolyte secondary battery includes a positive electrode (2) containing a positive electrode active material including a lithium-containing transition metal oxide; a negative electrode (1) containing a negative electrode active material capable of intercalating and deintercalating lithium; and a non-aqueous electrolyte including a solute and a solvent; wherein the solvent contains 50 volume % or more of gamma-butyrolactone with respect to the total volume of the solvent, and the positive electrode active material contains a phosphate salt M.sup.1PO.sub.4, where M.sup.1 is a metal element capable of having a valency of 3.