A bottle is a bottle formed of synthetic resin materials in a cylindrical shape with a bottom. A bottom wall portion in a bottom portion thereof includes a grounding portion positioned at an outer circumferential edge thereof, a rising circumferential wall portion connected to the grounding portion from an inside of a bottle radial direction and extending upward, a movable wall portion protruding from an upper end part of the rising circumferential wall portion toward the inside of the bottle radial direction, and a recessed circumferential wall portion extending upward from an inner end part in the bottle radial direction of the movable wall portion. The movable wall portion is arranged to be movable upward together with the recessed circumferential wall portion, around a connected portion with the rising circumferential wall portion. A plurality of ribs are arranged in the movable wall portion radially around a bottle axis.