A semi-finished product (31) includes a first curved portion on one end of a plate-shaped bridge portion (33), and a second curved portion (37) on the other end of the bridge portion (33). The second curved portion (37) includes at the end a second lock portion (51) to lock with a first lock portion (41). The bridge portion (33) and the inner circumferential surfaces of the first and second curved portions (35, 37) are pressure-contacted and caulked on the outer circumferential surface of the stabilizer bar (11) by first and second dies (61, 62). At least one of the inner circumferential surfaces (31c) of the first and second curved portions (35, 37) and the outer circumferential surface of the stabilizer bar opposed to the inner surfaces (31c) is formed with an anti-slippage portion (38). The inner circumferential surfaces (31c) of the first and second curved portions (35, 37) and the outer circumferential surface of the stabilizer bar (11) have an anti-slippage material (Co) therebetween.