PURPOSE: To mold readily a container with an elongated neck section, by stretching a preform, which will be molded into a hollow container, at a section thereof which will constitute the neck section of the hollow container by a stretching rod, and blow molding it while stretching a section where the barrel section will be formed.

CONSTITUTION: First an outer stretching rod 2 is projected down to stretch the section of a preform 1 by a predetermined ratio where the neck section of a hollow container will be formed. When the stretching of the neck section of the hollow container is completed, an inner stretching rod 3 is extended to form the barrel section of the hollow container while a pressurized gas is introduced, so that the aimed hollow container 5 is finally molded.