Input operation detection device and video projection device

The purpose of the present invention is to provide an input operation detection device which detects the strength of a touch without using a digital pen or an installation of a touch panel. To this end, provided is an input operation detection device, comprising: a light source which emits an emission light which has a width in a direction which is perpendicular to a touch operation plane; a sensor unit which receives reflected light which occurs when the emission light is reflected by an object to be detected which makes contact with the touch operation plane and carries out an input operation, said sensor unit outputting data of the intensity of the received reflected light and/or distance data based on the travel time of the reflected light; and a control unit which, on the basis of a change over time of the data of the intensity of the received light and/or a change over time of the distance data, outputs a first operation signal which indicates that the object to be detected has strongly contacted the touch operation plane or a second operation signal which indicates that the object to be detected has weakly contacted the touch operation plane.