Provided is a method for verifying holding members in a heating station equipped with a device for transporting the preforms. The device includes a plurality of movable supports circulating in a closed circuit and members for individually holding the preforms by their neck, where each of the holding members is borne by a movable support. The method includes setting the movable supports in movement to bring them successively into an acquisition zone, acquiring an image of each individual holding member in the acquisition zone, and automatically verifying the presence of a holding member on each of the images taken.

An injection blow molding machine includes: a stationary member that is fixed to a frame; a movable member that is movable with respect to the stationary member; a rotating member that is disposed between the stationary member and the movable member, rotates to face the movable member while gripping a preform after the preform is molded together with the stationary member, and rotates to face the stationary member after a final molding product is molded together with the movable member; and a detection unit that is attached to the stationary member, the rotating member, or the frame, and detects whether the final molding product is present between the stationary member and the rotating member.