PURPOSE: To form a protective frame for a young plant as well as to prevent a fall of sand and soil by a method wherein the young plant planted at the sloping ground is enclosed by the block having a heaped shape and the columnlike projections.

CONSTITUTION: A young plant 6 is planted at the sheathing mounting positions in the sloping plane. Irregular block having projections 1 and 2 and columnlike projections 3, 4 and 5 is raised up, the columnlike projections 3, 4 and 5 are directed at a right angle with respect to an inclination and the block is set in such a way as the young plant 6 is placed between the projections 3 and 5 at the bottom of the block. Then, another block is abutted against the former block and then the protective frame for the young plant 6 is formed by the sides 1 and 2 and the projection 4 and at the same time a frame of the sheathing for the young plant 6 is formed by the sides 1, 2 and the projections 3, 4 and 5. The front one of the two openings 7 made by the two blocks is used for growing the young plant 6 and rear one of the openings is covered with brushwood 8 etc. The rain water fallen on the slope plane 9 is flowed into the cavity 10 through the brushwood 8 and then flowed down in the cavity 10. The block can be applied as a preventive bank for a rockslide or a snowslide.