A vehicle-pedal backward-displacement preventing device. A pedal bracket has side plates each including a front end at which the pedal bracket is attached to the dash pane. A bulge protrudes in a protruding direction away from the other of the side plates. An operating pedal having a depressible portion is provided by its lower end portion. A guide member is associated with an upper end portion of the pedal bracket and a vehicle body member. The guide member causes the upper end portion of the pedal bracket to be downwardly displaced, upon displacement of the pedal bracket, whereby the pedal bracket is deformed with the side plates being made to buckle, so as to restrain the displacement of the depressible portion of the operating pedal toward a driver's seat. Each side plate has an aperture located in its region which includes a crest portion of the bulge, such that a strength of each side plate against a load is reduced most in the crest portion. Each side plate therefore can be made to buckle with the crest portion being displaced in the protruding direction.