An electrochemical device comprising an electrode assembly in which two types of electrodes are stacked or wound with separators interposed therebetween and an outer container that accommodates the electrode assembly; wherein electrode terminals extend to the outside from within the outer container. The films which cover the electrode assembly overlap each other on the outside of the outer peripheral portion of the electrode assembly, and the outer container is formed by bonding the films to each other. The portion of the films that overlap and are bonded to each other comprises a first sealed portion in which the films overlap and are bonded to each other in an overlapping state with the electrode terminals interposed therebetween, and comprises a second sealed portion in which the films are bonded to each other in a directly overlapping state without interposition of the electrode terminals.