PURPOSE: To enable one to walk on the surface of snow stably while wearing ski plates by mounting releasably a ski spike device of a antiskid projection to the ski plate.

CONSTITUTION: A ski spike device 3 of a antiskid projection is mounted releasably to a ski plate 1 behind a ski boot 2 or on the side of the ski boot. While a pile-like spike 4 on the ski spike device 3 is retreated above from the lower surface of the ski plate 1 in skiing, the spike 4 is projected downward from the lower surface of the ski plate 1 against a spring 5 except in skiing, i.e., in walking to hold the projecting state through the engagement with a stopper 6, so that one can stably walk on the surface of snow without slipping.