Abstract: The present invention relates to a plug-containing type internally threaded anchor to be set in concrete which is used to optionally and firmly fix hardware, such as ceiling members, floor members and wall members, to the surface of a concrete structure and it also relates to a method of producing the same which promises mass-production effect. The invention is characterized in that as a means for preventing the plug contained in the anchor body from accidentally slipping off owing to vibration, shock or other external forces exerted during transport or laying operation, the anchor body is formed with an internal thread by rolling whose internal diameter is smaller than the outer diameter of the plug, so that the crest portion of the internal thread bulging by a predetermined amount above the anchor body holds the plug in slip-off preventing condition.