In Japan, protective measures to reduce falls from scaffolds have been strictly applied within industry safety guidelines, and such measures have significantly decreased fatal accidents due to falls from scaffolds. However, the rate of fatal accidents from falls is still high in the construction industries. In order to examine further countermeasures to reduce such falls, the Japan Ministry of Health, Labour and Welfare established a committee in our institute. That committee$acute{i}$s work experimentally confirmed the effectiveness of using plastic sheets as a covering around scaffolds to protect against falls of construction materials (a method widely used in Japan). However, the workers fell from the space between the work platform and the plastic sheets very occasionally. Based on those results, the plastic sheets were improved for fall protection from the space, and the effect of the improved sheets was confirmed experimentally.