An organic electrolyte battery of this invention includes: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; an organic electrolyte comprising at least an organic solvent and a solute dissolved in the organic solvent; and an additive that suppresses an increase in internal resistance. The additive includes at least one of phthalazone and a phthalazone derivative. The addition of the additive to the battery suppresses an increase in internal resistance upon storage and upon charge/discharge cycling, thereby making it possible to improve the storage characteristics and charge/discharge cycle characteristic of the battery.