POLYGONAL BOTTLE

A polygonal bottle, and mouth, shoulder, drum, and bottom sections are formed in a bottle axial direction, the drum section including main wall sections connected via connecting sections in a circumferential direction about a bottle axis, in a lateral cross sectional view perpendicular thereto, a polygonal shape is formed, in which a panel section recessed inward in a radial direction, extending in the bottle axial direction and arriving at an upper portion of the mouth section side of the main wall section formed at the main wall sections of the drum section. A reinforcement protrusion protruding outward in the radial direction is formed at shoulder section connecting portions, a top surface directed outward in the radial direction is continued to an outer circumferential surface of the drum section with no step difference, and an upper surface directed upward is formed in a curved surface shape protruding upward.