A vehicle-pedal backward-displacement preventing device including: (a) a pedal bracket supporting an operating pedal having a depressible portion; (b) upper and lower attachments fixed to the pedal bracket, such that the pedal bracket is attached to a dash panel through the attachments; and (c) a guide member fixed to the pedal bracket or a vehicle body member and is operable to restrain, in event of backward movement of the pedal bracket together with the dash panel toward a driver's seat, the depressible portion of the operating pedal from being backwardly displaced toward the driver's seat, by causing a distal end portion of the pedal bracket to be downwardly displaced. The pedal bracket has a separation portion located in vicinity of the upper attachment, such that the pedal bracket is breakable at the separation portion by a load generated in the event of the backward displacement of the dash panel, thereby separating the upper attachment from the pedal bracket, and allowing the pedal bracket to be pivoted about the lower attachment in a direction causing the distal end portion of the pedal bracket to be downwardly displaced.