The present disclosure provides a high-output electrochemical device with a low internal resistance, the electrochemical device including a positive electrode, a negative electrode, and an electrolyte having lithium ion conductivity. The negative electrode includes a negative current collector and a negative electrode mixture layer supported on the negative current collector. The negative electrode mixture layer contains a conductive additive and a negative electrode active material reversibly doped with a lithium ion. A surface area A per unit mass of the negative electrode mixture layer and a mass B of the negative electrode mixture layer supported on a unit area of the negative current collector on one surface satisfy a relationship of 200≤AB≤1,400.