PROBLEM TO BE SOLVED: To provide a cutting blade cover device for preventing work interruption or failure due to entanglement of weed when tall weed is cut.SOLUTION: A weed cutting guide cover 4 is disposed directly above a cutting part, at a height position separated from a blade surface of a cutting blade by 60mm to 80mm. The weed cutting guide cover 4 covers the cutting part so that a rim ahead in an advancing direction of the device body protrudes beyond an outer periphery of a rotational cutting blade, and a part directly above the cutting part is made to incline, going up toward a rim that exists ahead, seen horizontally. Wheels 43R, 43L for holding the cover height position are disposed on rims on right and left sides with respect to a device body advancing direction of the weed cutting guide cover 4.