To open the space around a prime mover, and a space between rear wheels and a body frame, largely at a time, by providing a pivoting part directing to the left and the right width direction, at the front end lower part of a bonnet and a fender formed integral, and making the bonnet and the fender allowable to open and close integrally by making the pivoting part as the turning fulcrum.

In a riding work vehicle A, a prime mover 6 covered by a bonnet 2 is provided at the rear part of a body frame 1, while a driving part 5 is provided at the front part of the body frame 1. While a fender 3 to cover the upper part of the left and the right rear wheels 9 installed the the left and the right sides of the prime mover 6 is formed integral, a pivoting part 2a directing to the left and the right width directions is provided to the front end lower part of the fender 3, and the bonnet 2 and the fender 3 are made allowable to open and close integrally by making the pivoting part 2a as the rotating fulcrum. Consequently, the space around the prime mover 6, and the space between the rear wheels 9 and the body frame 1 can be opened largely at a time, the whole visibility is improved, and a cleaning such as the dust removing, and a maintenance such as a repair can be carried out easily.