The preform of the biaxially drawn, blow-molded bottle comprises polyethylene terephthalate layers 2 and at least a gas barrier layer 3 laminated with the polyethylene terephthalate layers. The gas barrier layer 3 extends downward from a level halfway to the height of the neck 4 including the neck ring 5, or at least from above the neck ring 5, down virtually to the lower end of body 6. The gas barrier layer 3 inside the wall of the neck 4 has an average thickness corresponding to a third (⅓) or less of the maximum thickness of the gas barrier layer 3 inside the wall of the body 6, allowing most of the gas barrier material to be located in the wall of the body 6. Thus, the gas barrier material is effectively utilized, and in the case of the heat-resistant bottle, the neck has the predetermined dimensions without fail after the whitening treatment.