An organic electrolyte capacitor with high energy density and high output power is disclosed which has a high capacity even at -20 DEG C. The organic electrolyte capacitor comprises a positive electrode, a negative electrode, and an electrolyte which is capable of transferring lithium ions. The positive electrode can reversibly support lithium ions and anions, while the negative electrode can reversibly support lithium ions. A mesoporous carbon material having a mesopore diameter of not less than 3 nm and a mesopore volume of not less than 0.10 ml/g is used as the negative electrode active material. Consequently, there can be realized an organic electrolyte capacitor which has a high discharge capacity even at such a low temperature as -20 DEG C while having a high voltage and a high energy density.