Abstract: The invention relates to a mobile thinning machine. It comprises according to the invention a two-wheeled drive unit (1) with motor and hydraulic unit and a logging unit (2) carried on a dirigible and driven supporting wheel (5), with driver's cab (8), pivotal boom (13), felling unit (15) and clamping bunk (20). The logging unit (2) is connected to the drive unit via an articulate frame steering (21) with a bracket (22) and a telescopic arm (24) extending therefrom. The articulate frame steering (21) permits the two units (1,2) to be put at an angle of more then 90.degree. relative to each other. The telescopic arm (24) houses necessary hydraulic and electric lines all the way to the logging unit (2) for operating this unit from the driver's cab (8). The telescopic arm (24) can be moved back over the drive unit (1), so that this unit together with the logging unit (2) forms a compact three-wheeled vehicle for transport between the thinning places.