Abstract: A method for stretch blow molding a wide-mouthed container, employing a preliminary stretching before stretch blowing without making an upper body portion thickened so as to thin the wall thickness from the connecting portion between the mouth portion and the body portion, thereby preventing the thickening phenomenon at the subjected portion. A preform having a large diameter mouth portion, a body portion and a bottom portion is injection molded within an injection mold. The preform is released from the injection mold in a state where the inside thereof is still in a high temperature while holding the mouth portion of the preform with a lip mold. Then, the preform is transferred to a blow mold as it is. Before the stretch blow molding step of the preform, a stretching rod is descended in a predetermined length to preliminary stretch the body portion in some extent.