Abstract: A chain saw sharpener including a base plate; a clamp affixed to the base plate for holding the bar of a chain saw in vertical orientation; a tubular guide member affixable on the base plate at a selected angle relative to the clamp and hence the chain saw; a file carriage provided with a top rod insertible into the guide member for reciprocal and rotational movement relative thereto and an underlying bottom rod having a pair of downwardly depending file support members for giving support to both ends of the file; and a circular file rotatably mounted within the support members. A handle affixed to the file permits full foxibility and positioning of the sharpener in relation to the teeth to be sharpened. The top rod of the file carriage is provided with a free end for convenient insertion and removal from the file guide.