A blow molding machine including at least a blow mold (12), wherein is introduced a preform (14) previously produced by injection molding, and a blow nozzle (22) for injecting pressurized air into the preform (14). It is equipped with a device for orienting the preform in the mold, the device including a grip member (30) adapted to grip the preform (14) by its neck (18) when it is engaged in the mold (12); a device (66) for driving in rotation the grip member (30); a device for detecting (70) at least a reference angular position of the preform (14); and a control device to cause the grip member to rotate until the detecting device detects the reference angular position of the preform.