PURPOSE: To easily set all of the edges at the right and left parts at the same angle so that a chain saw may cut a wood, etc., straightly by forming a structure of fitting a chain saw setting ruler to a guide bar by a magnet.

CONSTITUTION: A setting ruler main body is in a plastic made pipe shape, for instance, a plane 2 is of an elliptical shape and a small elliptical magnet 3 is fixed thereto. The plane 2 and the surface of the magnet 3 are taken in the same face and the angles of an A line and a B line are taken at 60°, for instance. A fine adjustment is executed by picking up the horn like place of the ruler and sliding it fore and aft, the space between a file and pipe 1 is made parallel and by pushing the file the setting can be performed at the same angle. By executing the setting like this the power can be displayed similar to a new machine at all times without being cut with its bent, because of the angles of all of the edges of the chain saw being the same.