A machine for chamfering the corner of an object comprising a rotating cutter arranged in a machine body and having cutting blades around the outer circumference of that portion of the rotating cutter which is projected from and tilted relative to an underside, a slide guide for slidably supporting the underside of the machine body and having guide planes perpendicular to each other and slidable along the corner of the object and also having a space formed between the planes and into which at least a part of the cutting blades of the rotating cutter is projected, a fixing means for connecting the machine body and the slide guide releasably from each other to adjust the cutting blades projected into the space between the guide planes of slide guide, and a stud means having a first end fixed to one of the machine body and slide guide at a position remote from the rotating cutter and serving to make the machine body and the slide guide swingable to each other when the fixing means is under release.