PURPOSE: To improve the coupling strength of a metallic round bar and a metallic plate by inserting through a shaft part of the metallic round bar which has provided plural projecting parts on the lower face of a flange part, into a round hole of the metallic plate, and subsequently, applying a pressing force to the upper face of the flange part.

CONSTITUTION: A shaft part 4 of a metallic round bar 3 having plural pieces of projecting parts 2 on the lower face of a flange part 1 is inserted through into a round hole 6 of a metallic plate 5, and fitted to the metallic plate 5 in the lower pat of a neck of the flange part 1. Subsequently, a linear 10 of the same thickness is placed on the periphery of the flange part 1, and the upper face of the flange part 1 is pressed in the direction with an arrow A by a pressing force of a press machine 11. In such a case, the projecting part 2 of the lower face of the flange part 1 is allowed to gnaw at the upper face of the metallic plate 5, and also, by the upper face stepped part 9 of the lower die 7, a wall 12 of the peripheral edge of the lower face of the round hole 6 is compressed by the round bar 3, and clamps the shaft part 4. According to such a method, the coupling strength of the round bar 3 and the metallic plate 5 is improved, and as for the round bar, inexpensive carbon steel is enough, and its manufacturing cost can be reduced.