Disclosed herein is a cooling member mounted between battery cells to remove heat generated from the battery cells during charge and discharge of the battery cells, wherein the cooling member includes a plate-shaped cooling fin configured to have a structure in which two battery cell contact portions disposed in tight contact with outer sides of the battery cells in a state in which the cooling fin is disposed between the respective battery cells are continuously formed in a horizontal direction (a lateral direction) and a coolant conduit configured to have a hollow structure in which a coolant flows, the coolant conduit thermally contacting the cooling fin, the coolant conduit being located at the outside of an electrode assembly receiving part of each of the battery cells when the cooling fin is disposed between the battery cells.