To provide a bottle which excels in transparency and which, even when filled with a carbonated beverage and heated for sterilization, keeps sulf-supporting and is not deformed.

This bottle 1 is formed of a polyester-based resin composition which consists of 99.5 to 99.999wt.% of a polyester and 0.001 to 0.5wt.% of a modified polyethylene. In warm-bath test of the bottle, in which the bottle is filled with a beverage containing carbonic acid gas to 2.5 gas volume at 23°C and immersed in a tightly stoppered state in a warm bath at 70°C, the dimensional change of the bottle in the direction of the height in the values before and after the immersion in the bath has been determined at not more than 5% and the dimensional change in the direction of the diameter of the drum part likewise has been determined at not less than 5%, thus the bottle retaining its self-supporting property.