The present invention is to improve productivity and maintain a predetermined switch contact gap between a sensing rod and a stopper after mounting the pedal switch in order to accurately detect the operational conditions as the pedal arm is operated, by fastening a pedal switch to a mounting bracket fixed to the car body in one touch insertion way.A device for fixing a pedal switch of a vehicle according to the present invention comprises a lock case 10 fastened to a mounting bracket 1 fixed to a car body; a return spring 20 disposed in the lock case 10; and a lock rod ring 30 disposed movably within a predetermined distance inside the lock case 10 and elastically supported by the return spring 20, and in which a sensing rod 42 of the pedal switch 40 is fastened.