1. A display apparatus capable of detecting that an arbitrary place of a display screen has been pointed by a human hand or a pointing member, the display apparatus comprising: display elements formed near intersections of signal lines and scanning lines respectively arranged in vertical and horizontal directions; image pickup units which pick up incident light in a predetermined range; D/A conversation circuits provided every a plurality of signal lines to supply pixel data for display to a plurality of signal lines associated therewith; amplifier circuits which output the picked-up image data in the image pickup units from pixels by using signal lines that are not supplied with pixel data, while the D/A conversion circuits supply pixel data to signal lines in order; and a pointer detection portion which detects a position pointed by a hand or a pointing member on the display screen, on the basis of the picked-up image data, wherein whenever the image pickup units perform image pickup, the pointer detection portion detects an image that indicates a pointed position, and when a diameter of the image is maximized, the pointer detection portion judges that the display screen has been pressed strongly by a hand or a pointing member.