An electrolyte for a non-aqueous electrolyte battery includes a non-aqueous organic solvent and at least lithium hexafluorophosphate as a solute, characterized by further including 10 to 1000 mass ppm of a phosphorus-containing acidic compound and 0.01 to 10.0 mass % of a difluorophosphate. The phosphorus-containing acidic compound is preferably at least one selected from the group consisting of HPF6, HPO2F2, H2PO3F and H3PO4. By the use of such an electrolyte, it is possible to provide the non-aqueous electrolyte lithium battery capable of maintaining high discharge capacity even after repeated charge/discharge cycles under a high temperature environment.