To make it possible to rationalize the production, save labor and power consumption and upgrade the accuracy of a product by providing a pressing roller which presses to the side the head part of a rail clamping shoulder protruding to the lower part of a stud hole at the bottom part of a concrete tie molding form.

A shoulder 3 is temporarily fixed, in a reversed upright state, at the bottom part of a tie molding form 4 and the head part 3b of the shoulder 3 is pressed using a fitted pressing roller 10. At the same time, the head part 3b is pressed downward to the lower part of a stud hole 5a in the head part 3b to temporarily fix the shoulder 3 more strongly. When the form 4 is release, the head part 3b can be drawn out of a space between the pressing rollers 10, 10 simultaneously with the releasing of the form 4, as the head part 3b of the shoulder 3 is only clamped from both sides by the pressing rollers 10, 10 with the spring force of a coillike spring. The temporary fixing jig 6 is mounted to the second surface of the bottom part 5 of the form 4 with the assistance of a fitting plate 14 and a fitting fitment in such a way that the jig 6 is easily removable. Thus it is possible to fit the shoulder 3 to the bottom part 5 of the form 4 in a secure, tight and simple manner.