PURPOSE: To obtain stable joint strength, and sufficient strength also to bending and torsional stress.

CONSTITUTION: The outer peripheral section of a sleeve 3 fitted externally on the jointing section of a deformed bar 2 is caulked to be set on the outer peripheral surface of the deformed bar 2 to be confronted with each other in the diameter direction, and the sleeve 3 is squeezed to place a pair of ribs 4, 4 extending in the axial direction between both sides. The compressive extra thickness 3a is brought in close contact with both the side surfaces of the rib 4 and at the same time, the thickness 3a is pressed in recessed sections 6 between nodes 5, and the deformed bar 2 and the sleeve 3 are joined to each other. On the outer peripheral section of the sleeve 3, four squeezed traces 5b are formed.