An input operation detection device configured to detect an input operation by a user to an image displayed on a projection surface disposed in an XZ plane in a three dimensional space defined by X, Y and Z axes and divided in a first direction, the X axis direction, into a first image (image R) and a second image (image L), the device comprising: a first imaging section at a first installation position that includes a first light-emission part, a first imaging optical system, a first image sensor and a first arithmetic part to acquire a first depth map based on a time of flight method; a second imaging section at a second installation position that includes a second light-emission part, a second imaging optical system, a second image sensor and a second arithmetic part to acquire a second depth map based on a time of flight method; and a processor that is configured to detect the input operation based on the first and second depth maps, the first imaging section and the second imaging section are arranged such that the optical axis of the first imaging section and the optical axis of the second imaging section do not intersect each other between the first and second imaging sections (13, 14) and the first and second images (images R and L), the first imaging section being configured to capture a part of the image including the first image (image R) and the second imaging section being configured to capture a part of the image including the second image (image L), the first imaging section being configured so that an optical axis of the first imaging optical system intersects with the first image (image R) at a first intersection point on a same side of a center of the first image (image R) as the first installation position of the first imaging section, and the second imaging section being configured so that an optical axis of the second imaging optical system intersects with the second image (image L) at a second intersection point on a same side of a center of the second image (image L) as the second installation position of the second imaging section. a first imaging section at a first installation position that includes a first light-emission part, a first imaging optical system, a first image sensor and a first arithmetic part to acquire a first depth map based on a time of flight method; a second imaging section at a second installation position that includes a second light-emission part, a second imaging optical system, a second image sensor and a second arithmetic part to acquire a second depth map based on a time of flight method; and a processor that is configured to detect the input operation based on the first and second depth maps, the first imaging section and the second imaging section are arranged such that the optical axis of the first imaging section and the optical axis of the second imaging section do not intersect each other between the first and second imaging sections (13, 14) and the first and second images (images R and L), the first imaging section being configured to capture a part of the image including the first image (image R) and the second imaging section being configured to capture a part of the image including the second image (image L), the first imaging section being configured so that an optical axis of the first imaging optical system intersects with the first image (image R) at a first intersection point on a same side of a center of the first image (image R) as the first installation position of the first imaging section, and the second imaging section being configured so that an optical axis of the second imaging optical system intersects with the second image (image L) at a second intersection point on a same side of a center of the second image (image L) as the second installation position of the second imaging section.