A blow molding apparatus includes a machine bed, an upper base disposed at intervals in a vertical direction from the machine bed, a transport plate configured to rotate at a height position of the upper base to convey the preform between an injection molding part and a blow molding part, and an elevation mechanism configured to move the transport plate or the upper base up and down in the vertical direction with respect to a mold disposed on the machine bed. A support pillar includes a height adjusting part configured to adjust a stroke of the transport plate or the upper base in the vertical direction with respect to the machine bed.