Abstract: A selector pen for touch screen includes a barrel having a light emitter mounted therein to be turned on or off through turning of a switch rotatably connected to a rear end of the barrel. The switch includes a base defining a non-circular insertion hole, a movable rod being fixedly received in the insertion hole of the movable rod and having an inclined top formed into a spiral guide surface, and a cap being rotatably covered onto the base and having an internal projection. When the cap is turned, the projection slides along the spiral guide surface to gradually depress the movable rod for the same to electrically make the light emitter. The switch has simplified structure and the spiral guide surface defines a definite range of turning for the cap.