A connecting opening portion is provided at the portion that is an outer circumferential portion of a hollow-structured operating pedal and is connected to connecting links inside the connecting opening portion, a reinforcing member having a U-shaped section is integrally weld-joined so as to open outward. End portions of the connecting links are inserted inside the reinforcing member, and are relatively pivotablly connected by a first link pin. Accordingly, the rigidity of the operating pedal is improved, and at the same time, the stress concentration is relieved, whereby buckling and deformation are suppressed. As a result, the plate thickness of the hollow-structured operating pedal can be kept small to minimize the weight thereof, and also, the width dimension of the operating pedal in the vehicle fore and aft direction can be reduced to achieve a compact size.