PURPOSE: To form a blank material to be formed into the titled gear having no defects in the tooth parts by inserting the blank material between an upper die presser connecting to a spindle and a bottom die having a tooth die in the base of an engraving space and rotating and screwing down the spindle in the helix direction toward the radial outside of the tooth trace of the tooth die thereby rolling the material.

CONSTITUTION: The blank material 8 to be formed is inserted between the upper die presser 2 connecting to the spindle 1 and the lower die 4 having the spiral tooth die 6 in the base of the engraving space 5. The spindle 1 is inclined in the axial center by an angle θ and is rotated and screwed down in the helix direction toward the radial outside of the tooth trace of the die 6. The blank material is subjected to rotary forging by a working face 3. The meterial 8 enters thoroughly the tooth 6 and is thus made into the satisfactory spiral bevel gear without having the defects such as under fill and laps in the tooth parts.