When an imaging apparatus (30) captures an image of a finger performing an operation on a visual confirmation screen (S2), an operation determining unit (73) of a computer display device (1) mounted on eyeglasses (10) determines the contents of the operation performed by the finger based on image data obtained by the imaging apparatus (30). A positional data generating unit (74) generates positional data of the finger based on the image data. Based on data concerning the determined contents of the operation performed by the finger, the generated positional data of the finger, and reference data concerning the visual confirmation screen stored in a storage unit (90), an input control unit (76) determines the contents of an inputted instruction corresponding to the operation performed by the finger, and controls an original screen to be displayed on an display apparatus (20) in accordance with the determined contents of the inputted instruction.