Electrochemical device comprising electrode lead having protection device

Disclosed is an electrochemical device comprising an electrode assembly having a cathode, anode and an electrolyte, the electrode assembly being enclosed with a casing having an inner surface and an outer surface, wherein the electrochemical device further comprises a protection device to which either or both of a cathode lead for connecting a cathode with an outer terminal and an anode lead for connecting an anode with an outer terminal are connected electrically, the protection device is disposed at a sealing region between inner surfaces of the casing, and the sealing region of the casing is folded so that the sealing region having the protection device is layered on a lateral surface of the casing.