An apparatus for stretching a plastic film longitudinally thereof, the apparatus comprising: plastic film feeding means by which the plastic film is fed longitudinally thereof and intermittently, the plastic film having opposite surfaces and opposite side edges; a stretching member and a board disposed on opposite sides of the plastic film to be opposed to the surfaces of the plastic film and to each other when the plastic film is fed longitudinally thereof; and drive means by which the stretching member is advanced toward the board to be pressed against the plastic film and the board between the side edges of the plastic film to stretch the plastic film longitudinally thereof when the plastic film is stopped temporarily, the stretching member being then retracted from the board and kept apart from the plastic film by the drive means, wherein the stretching member comprises a plate including a tapered linear edge and extending widthwise of the plastic film, the linear edge being opposed to the board, the plate being advanced toward the board so that the linear edge can be pressed against the plastic film between the side edges of the plastic film, the plate being then retracted from the board so that the linear edge can be kept apart from the board, characterized in that the apparatus further comprises: additional drive means by which the plate is moved slightly and longitudinally of the plastic film and; a control device connected to the drive means and the additional drive means, the drive means and the additional drive means being controlled by the control device so that the plate can be moved slightly by the additional drive means after being retracted and then advanced and retracted again. plastic film feeding means by which the plastic film is fed longitudinally thereof and intermittently, the plastic film having opposite surfaces and opposite side edges; a stretching member and a board disposed on opposite sides of the plastic film to be opposed to the surfaces of the plastic film and to each other when the plastic film is fed longitudinally thereof; and drive means by which the stretching member is advanced toward the board to be pressed against the plastic film and the board between the side edges of the plastic film to stretch the plastic film longitudinally thereof when the plastic film is stopped temporarily, the stretching member being then retracted from the board and kept apart from the plastic film by the drive means, wherein the stretching member comprises a plate including a tapered linear edge and extending widthwise of the plastic film, the linear edge being opposed to the board, the plate being advanced toward the board so that the linear edge can be pressed against the plastic film between the side edges of the plastic film, the plate being then retracted from the board so that the linear edge can be kept apart from the board, characterized in that the apparatus further comprises: additional drive means by which the plate is moved slightly and longitudinally of the plastic film and; a control device connected to the drive means and the additional drive means, the drive means and the additional drive means being controlled by the control device so that the plate can be moved slightly by the additional drive means after being retracted and then advanced and retracted again. additional drive means by which the plate is moved slightly and longitudinally of the plastic film and; a control device connected to the drive means and the additional drive means, the drive means and the additional drive means being controlled by the control device so that the plate can be moved slightly by the additional drive means after being retracted and then advanced and retracted again.