Abstract: A firewood processor with a tightenable saw chain, which processor comprises a frame arranged to support the firewood processor to a base, such as the ground, and a saw for sawing wood raw material in a transverse direction into an intermediate product of a desired length. The saw comprises a saw chain, a flange for guiding said saw chain and a sprocket, which is arranged to convey the driving force to said saw chain. The firewood processor further comprises a splitting section for splitting the intermediate product of a desired length in the longitudinal direction into a desired size, which splitting section comprises a splitting wedge and means for splitting the intermediate product of a desired length by means of the splitting wedge. In addition, the firewood processor comprises automatic means for tightening the saw chain of said saw and for maintaining the tightness.