Method of producing non-aqueous electrolyte secondary battery

A non-aqueous electrolyte secondary battery includes: a positive electrode; a negative electrode that includes an active material containing a titanium oxide having a lithium ion storage potential of 1.2 V or higher (versus Li/Li+); a non-aqueous electrolyte containing a lithium salt including lithium hexafluorophosphate and lithium tetrafluoroborate; and a non-aqueous solvent including ethylene carbonate, cyclic carboxylic acid ester, or cyclic carbonate having four or more carbon atoms, and chain carbonate. The content of ethylene carbonate in the entire non-aqueous solvent is 5 to 20 vol %, and the concentration of lithium tetrafluoroborate in a non-aqueous electrolyte solution is 0.05 to 0.5 mol/l.