An input pen (60) of the present invention is an input pen used for performing an input to a touch-panel-integrated liquid crystal display device (100) (display device). The liquid crystal display device (100) includes a plurality of photosensitive elements (30) that senses light transmitted through a panel surface. The photosensitive elements (30) detect a position of input by sensing an image on a surface of a display panel. The input pen (60) includes a retroreflective element (61) at its tip that is to be in contact with the display panel. The retroreflective element (61) is made up of a spherical glass (62) (spherical transparent member) and an elastic reflective element (63). In this way, it is possible to provide an input pen which is to be used with a touch-panel-integrated display device and which makes it possible to perform a more accurate position detection.