Polyethylene terephthalates of the present invention are excellent in mechanical strength, heat resistance and transparency, and therefore blow molded containers molded from the present polyethylene terephthalate are excellent in high temperature filling properties when they are filled with juice, refrigerant beverage, carbonated beverage, seasonings, etc. Furthermore, the blow molded containers prepared from the present polyethylene terephthalates have such characteristic features that they are free from thermal deformation at the time when they are subjected to high temperature filling, they are readily subjected to sterilization treatment and hence excellent in high speed filling properties.