Provided is an electrochemical capacitor which has low DC internal resistance, and which minimizes increase in the DC internal resistance due to a high temperature experience. The electrochemical capacitor is provided with a positive electrode having a positive electrode active material layer containing activated carbon, a negative electrode having a negative electrode active material layer containing a spinel-type lithium titanate, and a separator holding a non-aqueous electrolytic solution containing a lithium salt between the positive electrode active material layer and the negative electrode active material layer, a 100% discharge capacity of lithium titanate being set to within a range of 2.2 to 7.0 times a 100% discharge capacity of activated carbon. During charging and discharging of the electrochemical capacitor, only the area near the surfaces of lithium titanate particles are utilized, lowering the DCIR and improving the stability of the DCIR.