A screw adjusting apparatus includes a positioning control device for outputting rotation instructions to a designated position based on a rotation detection signal; an image sensing section; a visual recognition section for processing a video signal outputted from the image sensing section so as to measure position of an object; a screw feeding amount calculating device for deciding a feeding amount of the screw so as to place the object at a predetermined position according to position information outputted from the visual recognition section and the information of the object which has been moved by contact between the screw and a tool; and an instruction control device for issuing instructions to the positioning control device based on a decided feeding amount of the screw.
