A switch mechanism for an electric power tool, comprising: a linear slider received in a switch case so as to be moved manually in a first direction against the biasing force of a return spring; an actuating pin carried by the linear slider so as to be moveable along a second direction perpendicular to the first direction; a pair of direction converting levers crossed in the manner of a pair of scissors by a pivot pin mounted on the switch case, the actuating pin being located adjacent to first ends of the direction converting levers; a pair of lateral sliders engaged by second ends of the direction converting levers and allowed to move in the second direction; a first contact set including contacts carried by the linear slider and the wall surface of the switch case for mutual cooperation as the linear slider is moved in the first direction; and a second contact set including contacts carried by the lateral sliders and the wall surface of the switch case for mutual cooperation as the lateral sliders are moved in the second direction; the actuating pins being moveable between the first ends of the direction converting levers so as to selectively actuate one of the direction converting levers and the associated one of the lateral sliders through movement of the linear slider along the first direction via an engagement between the actuating pin and the first end of the associated one of the direction converting levers.