Abstract: A safety device for use on chain saws to prevent one-handed operation of the saw. A swingable bar structure is carried on the saw housing to connect with an engine carburetor throttle arm. Before the engine can develop sufficient power to move the cutter chain the user must manually draw the bar structure to a specific position alongside a hand grip structure on the saw housing. One of the user's hands will engage the safety device bar structure; the other hand will operate a trigger mechanism. Both hands must be used before the cutter chain can begin to move.