The invention is intended to provide an excavation teaching device for a construction
machine which can realize easy confirmation of a proper target excavation surface and increase the working efficiency during excavation even in work of forming the face of slope in complicated three-dimensional landforms. A display unit (46) displays, as an image in a first screen area (46a), a plurality of small plane surfaces G constituting a three-dimensional target
landform and illustrations of a body S of the construction
machine and a bucket B as an excavating tool at a fore end of an operating mechanism. Also, the display unit discriminatively displays in the first screen area, as a target excavation surface TG defined by a small plane surface along which excavation is feasible, one of the plurality of small plane surfaces constituting the three-dimensional target
landform, which satisfies that the direction normal to the one small plane surface is parallel within a range of allowable error to a plane in which the operating mechanism operates. A panel computer (45) displays, on the display unit (46), a line resulting from projecting a line normal to the target excavation surface, selected from among the plurality of, small plane surfaces constituting the three-dimensional target
landform, and the direction in which the operating mechanism of the construction
machine operates with current orientation thereof, as well as relative positional relationships among the body of the construction machine, the position of the operating mechanism and the target landform.