In a synthetic resin blow molded bottle, reduced pressure absorbing panel portions and column portions are formed alternately in the circumferential direction. Each column portion has a diameter that gradually increases downward and that remains substantially constant vertically. Each reduced pressure absorbing panel portion includes a pair of panel side edge portions, which is bent to the inner side from the adjacent column portions, a panel surface portion, which connects the pair of panel side edge portions, and a panel lower edge portion, which is bent to the outer side from a lower end edge of the panel surface portion. The panel surface portion of each reduced pressure absorbing panel portion includes a panel upper-side surface portion, whose diameter gradually increases downward, and a panel lower-side surface portion, which connects the panel upper-side surface portion and the panel lower edge portion and which has a substantially constant diameter vertically.