Method for manufacturing synthetic resin container and synthetic resin container

A method for manufacturing a synthetic resin container, the synthetic resin container being manufactured by blow molding a composite preform including a preform main body having a bottomed cylindrical shape and a covering material layer laminated on an outer peripheral surface side of the preform main body, the method comprising:

• heating the composite preform to bring the covering material layer into a molten state or a semi-molten state while softening the preform main body to be stretchable;
• subsequently molding the composite preform into a predetermined container shape by using a blow molding die in which an edge portion formed by providing a step on a cavity inner peripheral surface extends along a predetermined direction;
• and
• providing, in the covering material layer to be molded integrally with the preform main body, a thin portion molded by being brought into pressure contact with the edge portion.