The invention relates to a forest machine, comprising a chassis having a first chassis and a second chassis pivoted consecutively by a central pivot, first sets of wheels arranged in connection with the first chassis, an engine fitted in connection with the first chassis, a load space supported on the second chassis extending at least partly below an upper surface of the second sets of wheels, power transmission transmitting power to the second drive wheel of the second sets of wheels, wherein the second chassis includes two longitudinal parts attached to each other at least in front of the load space, which longitudinal parts are at a distance from each other in lateral direction of the forest machine at least over a partial length of the load space, in which forest machine the load space extends between the longitudinal parts in vertical direction of the forest machine.