A fastening frame (6) for providing a work vehicle with a lower blade (5) comprises a frame structure (7) having a front part (7') to be directed in a direction of a front end of the work vehicle and a rear part (7") to be directed in a direction of a rear end thereof, at least one locking device of a front part (6') of the fastening frame (6) arranged in connection with the front part (7') of the frame structure (7) for fastening the fastening frame (6) at its front part (6') to the work vehicle, at least one locking device of a rear part (6") of the fastening frame (6) arranged in connection with the rear part (7") of the frame structure (7) for fastening the fastening frame (6) at its rear part (6") to the work vehicle, and means for fastening the lower blade (5) to the fastening frame (6). The locking device of the front part (6') comprises a first locking device part to be fastened to the work vehicle and a second locking device part detachable from the first locking device part and fastened to the frame structure (7) of the fastening frame (6), and the locking device of the rear part (6") comprises a first locking device part to be fastened to the work vehicle and a second locking device part detachable from the first locking device part and fastened to the frame structure (7) of the fastening frame (6).
