PURPOSE: To suppress to apply unnatural force to gap parts at the cutting of grooved rectangular block and to prevent gaps from being opened by forming grooves for cutting on a part of a nonmagnetic body on a grooved butt surface, connecting and butting respective grooves, penetrating a hollow circular ring into a winding groove, and then charging the cutting grooves with adhesives.

CONSTITUTION: Winding grooves 15, front adhering grooves 16, winding window grooves 17, and back ashering grooves 18 are formed on the grooved rectangular blocks 31a, 31b. The cutting grooves with depth (d) are formed on the nonmagnetic body on the butt surface and all the winding groove 17 and adhering grooves 16, 18 are connected. The blocks 31a, 31b are butted and fixed, and after inserting an adhering block 20 and the hollow circular ring 32 into the back groove 18 and the winding window 17 respectively, the adhesives is made to flow from slice grooves 30 to charge all the grooves with the adhesives. After hardening the adhesives, the butt block 31 is cut along a chain line. Consequently, the gaps are not opened at the cutting of the butt block 31.