PURPOSE:To simplify the forming work of a vegetation foundation on a face of slope, by a method wherein grooves are formed at intervals in a hard slope ground with a jet of water, and the grooves are filled and the whole of a face of slope is covered with a vegetation material. CONSTITUTION:Grooves 2 are formed in a hard slope ground 1 at intervals in a vertical direction, and the groove recess is excavated with a jet of water to form a vertical cut surface 2a and a horizontal cut surface 2b of the groove 2. The shape of the groove 2 may be a round hole or groove. The interior of the groove 2 is filled with a vegetation material 4, the whole surface of the face of slope is covered with the vegetation material 4, and the vegetation material is prepared by mixing a fertilizer, a fiber material, a self-adhesive, and seeds in cultivated soil. This enables simplification of a work of forming a vegetation foundation on the face of slope.