PURPOSE: To obtain a highly efficient radiator formed through press-fitting a fin mechanically on a substrate by installing a specific fin on an aluminium substrate forming a protruded rail having a stopper.

CONSTITUTION: When a fin 2, which a cutout 12 fitted at both the side plate 11 and the fitting portion 7 in order that the fin 2 can slide on a protruded rail 10 on a substrate 1 consisting of an aluminium material forming the rail 10 having a stopper 9 stretching along both sides of the top, is inserted into the rail 10 of the substrate 1 in the cutout 12 being formed integrally, the fin 2 is brought into face contact with the substrate 1 at the fitting portion 7 and is fixed on the substrate 1 by deforming the stopper 9.