Abstract: One object is to provide an electrochemical device having a small inner resistance and a high reliability in a high temperature and a high voltage. In accordance with one aspect, the electrochemical device of the present invention includes a positive electrode and a negative electrode. At least one of the positive electrode and the negative electrode includes a current collector layer and an active material layer formed on at least one surface of the current collector layer, and the active material layer includes electrode active material bodies and a mixture film formed between the electrode active material bodies, the mixture film having a thickness of 0.1 ?m to 0.4 ?m.