A non-aqueous solvent is provided that includes ethylene carbonate in a range from 5% or more to less than 60%, propylene carbonate of 40% or less, and diethyl carbonate of 40% or more, as mass ratios. The non-aqueous electrolyte compositions are formed by further adding an electrolytic salt and, if necessary, unsaturated cyclic carbonic ester and a high molecular compound into the non-aqueous solvent. A non-aqueous electrolyte secondary battery is formed by using the non-aqueous electrolyte compositions.