The invention provides a trigger switch which allows main contacts double in series to be used as two poles with a large capacity and a long life, comprising fixed contacts forming main contacts double in series and functioning as a switch for supplying a motor with power and slide plate parts connected to the fixed contacts; and movable contacts provided in an actuator interlocking with an operation part and auxiliary contacts sliding on the slide plate parts. Drawing the operation part causes the actuator to make a clockwise movement to make the movable contact come into electric contact with the fixed contact to supply the motor with power, simultaneously making the auxiliary contact bridge over the slide plate parts to achieve electric contact to make no potential in the contact between the movable contact and the fixed contact. Releasing the operation part makes the actuator to make a counter-clockwise movement and makes the movable contact separate from the fixed contact, simultaneously making the auxiliary contact bridging over the slide plate parts cause a break of the contact with the slide plate part and the movable contact on the auxiliary contact contacts with the fixation contact which maks the motor in short circuit condition.