A preform molding method and apparatus which can utilize a part of an injection mold to crystallize a neck of a preform. A rotary disc includes a plurality of neck cavity molds. An injection molding station, first heating station, second heating station and cooling/removing station are located at the respective positions where the neck cavity molds stops. The injection molding station injection molds a preform having a neck. The preform is sequentially conveyed the first and second heating stations while being held by neck cavity molds at the neck. Each of the heating stations heats the neck cavity molds so that the neck of the preform is heated up to a temperature of crystallization. Thereafter, the cooling/removing station cools the neck cavity molds. After the cooling step, the preforms are released and removed from the neck cavity molds. Thereafter, the neck cavity molds are returned to the injection molding station.