PURPOSE: To provide a cooling fin acting as a structure as well as a thermal radiator in which a thermal radiating area of the thermal radiator per unit volume is increased, its size is small and it has a high thermal radiating capacity.

CONSTITUTION: A cooling fin is constructed such that a part corresponding to a structure 1 and another part corresponding to a thermal radiator 2B are separately formed, each of them is provided with flat surfaces 1C, 2C contacted to each other and these parts are contacted at the flat surfaces 1C, 2C and integrally connected to each other. At this time, the thermal radiator 2B is made of aluminum alloy extruded material having a grid-like section composed of many hollow rectangular cylinders in respect to an air aeration direction.