To comfortably perform grooving work in an easy posture, by providing a grooving machine capable of respectively adjusting the height of a seat surface of a boarding part and a position of a holding member (a grip) for holding a machine body in response to a worker by stature and an intention of the worker, in the riding grooving machine provided with the boarding part for allowing the worker to board by straddling or sitting above the substantially middle of a driving part and a grooving part, with any one constitution of a constitution for arranging the driving part in front and the grooving part in the rear or a constitution for arranging the grooving part in front and the driving part in the rear.

This grooving machine is characterized by arranging a mechanism for vertically adjusting the height of the seat surface of the boarding part by the stature and the intention of the worker and a mechanism for longitudinally adjusting the boarding part for allowing the worker to board in the advancing direction or the holding member (the grip) for holding the machine body equipped in a part of the boarding part.