Abstract: A sharpening device for supporting a file for sharpening the cutting elements of a chain saw. The device includes a base portion that is removably secured to the chain bar of the chain saw, and a top guide portion slidably mounted on the base portion and for supporting the file. The top guide portion moves between a first position at the chain for sharpening one of the cutting elements and a second position away from the chain to permit indexing of the chain to locate another cutting element for sharpening. In one embodiment, the base portion includes two sidewalls, and the chain bar is clamped between the sidewalls. In an alternate embodiment, the base portion includes a magnet for holding the base portion to one side of the chain bar, and further includes two flat pins that project from the base portion for resting on the chain bar.