An object of this invention is to provide a highly safe secondary battery employing a non-flammable electrolyte solution. The secondary battery has a positive pole comprising an oxide for storing and releasing lithium ions, a negative pole comprising a carbon material for storing and releasing lithium ions, and an electrolyte solution. The electrolyte solution comprises 1.5 mol/L or more of a lithium salt, or 1.0 mol/L or more of a lithium salt and 20% by volume or more of a phosphate ester derivative.
