PURPOSE: To prevent the occurrence of a snowslide by forming plural drain holes at given intervals on a base spreaded on a slope and plural projections at given intervals on the lower surface of the base, and inclining artificial lawns in one direction to be plantedly provided on the upper surface of the base.

CONSTITUTION: Plural drain holes 3, having an inner diameter of about 10mm, are formed at given intervals on a base 2 composed of resin such as polyurethane foam etc. Plural projections 4, having a height of about 5mm, are formed at about 20mm intervals on the lower surface of the base 2. Artificial lawns 5 are inclined about 10-30° in one direction to be plantedly provided on the upper surface of the base 2. Then the base 2 is fixed with adhesive, etc., so that the artificial lawns 5 can face the top side of an inclined floor 1. This can surely prevent the sliding of a snow layer on the inclined floor.