The invention provides a cooling fin that does not require flatness management (=straightness management) of a heat transfer portion during processing or assembling and that is suitable for dispersing the physical stress that occurs in response to the external environment, thereby minimizing deformation of the heat transfer portion, and a cooling structure comprising the cooling fin, and a battery module comprising the same. A cooling fin according to the present disclosure includes: a body having a rectangular shape; a first extension part protruding from an edge of an upper portion of the body and extending in one direction at a right angle with respect to the body; and a second extension part protruding from an edge of a lower portion of the body and extending in one direction in a step form with respect to the body, wherein the second extension part is divided into a plurality of slits.