PURPOSE: To prevent deformation at the time of firing by individually adjusting the filling quantity of raw material in a middle leg and the one in an outer leg respectively and equalizing the forming density of the middle leg and that of the outer leg.

CONSTITUTION: Lower punches 3, 4 for an outer leg is fixed to a solid plate 6. A lower punch 5 for a middle leg passes through the solid plate 6 while being vertically movable and performing an upper limit by a filling adjusting nut 11 and performing a lower limit by a wear plate 12. A punch 5 for the middle leg is pushed up by a core rod 13 while being positioned by the filling adjusting nut 11 and set up at a higher position than the lower punches 3, 4 for the outer leg. And a ferrite raw material 15 is filled. At the time of compression, an upper punch 14 is pushed down so as to put the respective lower punches 3 to 5 on the same level. At this time, the wear plate 12 hits a sliding block 7 so as to put the lower punch 5 for the middle leg at the same level with the lower punches 3, 4 for the outer leg. Thereby, forming density of the middle leg and the outer leg can be equalized so as to prevent deformation at the time of firing.