Abstract: A blow gun includes a body with first and second paths, a trigger, a control unit, a first spring, a second spring and a first pin. The control unit includes a control member, a bar, a seal ring, an end member, a collar and a fastening member. The control member is received in the first room and has a slot located corresponding to the first hole. The end member is connected to the control member and the seal ring is mounted to the end member to seal the communication between the first and second paths. The first spring is biased between body and the control unit. The second spring is biased between the body and the trigger. The first pin extends through the first hole and is movable in the slot of the control member. The two springs share the force applied thereto to have a long service life.