An input device includes a transparent display panel configured to display a graphical interface, an input plate disposed above the display panel and composed of a material that transmits the graphical interface and allows infrared light to propagate through the input plate, an infrared-emitting unit disposed in contact with the input plate and configured to emit the infrared light into the input plate via a contact surface of the input plate, and an infrared detection unit disposed below the input plate and configured to detect diffused light of the infrared light which is generated at the input plate when the input plate is touched.