PURPOSE: To produce products free from looseness in an automatic flow operation, by forming stepped parts at both ends of a fitting rod obtained by bending a linear steel bar in a U-form, mounting the bar on receiving jig by specifying the height of the stepped parts from the upper surface thereof, and calking by keeping the substrate in raised position with the steppped parts.

CONSTITUTION: The both ends 3, 4 of a fitting rod 2 obtained by bending a linear steel bar in a U-form are compressed from above and below by a press, and stepped parts 6 of compressed parts 6 of which width is smaller than the outside diameter are formed, and this rod is mounted on a receiving jig 7. At this time, the position from the upper surface 8 of the receiving jig to the stepped parts 6 is set higher by a face side calking allowance a. When a substrate 9 having through- holes 10, 10 is dropped from above and fitted, the substrate is held in the upper position at a spacing of the calking allowance a, and the head part 11 projecting from the substrate upward becomes a back side calking allowance b. When the pressing jib placed in the upper part is lowered to compress, the part surrounded by the head part 11, receiving jig 7 and substrate 9 is bulged out in the radial direction to be secured firmly.