Effects of light for different cultivation processes on fruit-body production of the white strain of Flammulina velutipes were examined. (1) Light treatment for "Baiyo" (spawn running) process at low intensity slightly increased the yield of fruit-bodies. (2) If the cultures after "Kinkaki" treatment were incubated under total darkenss in "Medashi" room for induction of budding, the appearance of buds were delayed, and tiny buds with rudimental pilei were formed in these cultures. The number of buds was increased with increasing light intensities. The optimal light intensities for producing suficient number of buds and for maximum yield of fruitbodies were 30 and 10 lux, respectively. (3) The dark cultivation in "Narashi / Yokusei" process (for acclimating the mushroom to reduced humidity, and for equalizing the size of fruit-bodies) produced low quality and irregular size of fruit-bodies. The optimal intensity for pileus development for this process was 30〜100 lux, but that for stipe elongation was estimated to be 2〜10 lux. (4) The optimal light intensity producing high quality fruit-bodies during "Seiiku" process (growing up) was estimated to be 2〜10 lux. However, the pileus diameter was increased with increasing light intensities, up to 200 lux.