Abstract: An injection mold (9?) of a plastic preform comprising a first part (12) and a second part (13), fixed to each other, and a third part (14); wherein the third part (14) is provided with a molding cavity (41?) defining an axis (Y?) and is adapted to be integrally fixed to a first surface of a supporting frame of the mold; wherein the second part (13), arranged between the third part and the first part, is adapted to slide along said axis to close or open the cavity; wherein the first part (12) comprises a longitudinal rod (55) adapted to slide along said axis (Y?) through a second surface of the supporting frame, opposite to and spaced apart from the first surface; wherein the second part (13) is provided with: —a guiding cage comprising a first plate (18), provided with a through hole through which the longitudinal rod can slide and configured to abut on said second surface; a structure (18?); parallel guiding rods (16) fixed at a first end thereof to said first plate and fixed at a second end thereof to the