Blow molding device and method for manufacturing a container

A method for manufacturing a synthetic resin container, comprising:

• tightly fitting a blow nozzle into a mouth tube portion of a preform in a bottomed cylindrical shape which is installed into a mold for blow molding;
• and feeding a liquid into the preform from a pressurized liquid feeding unit through the blow nozzle so as to shape the container into an expanded shape along a cavity surface of the mold, the method comprising:
• after the shaping of the container, drawing back the liquid inside the container to a pressurized liquid feeding unit side by means of a suckback mechanism disposed at a predetermined position in a liquid feeding channel from the pressurized liquid feeding unit to the mouth tube portion of the preform;
• closing the feeding channel by means of a valve mechanism disposed on the downstream side of the suckback mechanism;
• introducing a gas into the container to so as restore, to its original shape, the volume reduction deformation of the container resulting from the drawing back of the liquid;
• and adjusting a headspace inside the container through the amount of volume change associated with the volume reduction deformation.