A portable drilling device for use in horizontal boring through a substrate beneath an impediment includes a motor mounted on an inclined stabilizer bar. The inclined stabilizer bar includes a handle for use by the operator of the drilling unit which allows the operator to guide the unit during operation. A shaft is operatively mounted on the motor and is rotatably carried by the stabilizer bar. The shaft is in turn attached to an auger which is rotatably carried within a bearing housing assembly that is attached to the inclined stabilizer bar at a predetermined angle. A skid shoe is mounted underneath the shaft-auger attachment point and is attached to both the housing and the inclined stabilizer bar, whereby, when the motor is engaged the shaft and the auger are rotated in order to bore a horizontal opening through the substrate beneath an impediment such as a sidewalk or driveway.