To stabilize the berry production in a dioecious Japanese wild grape, Vitis coignetiae Pulliat, we studied the flowering patterns in female and male plants and the effects of timing and frequency of artificial pollination on fruit set and berry quality. The flowering periods of female and male plants were ten and nine days, respectively. The highest fruit set in the fruit cluster (54.6%) after performing artificial pollination twice was obtained using the pollen of male plants on the second and fifth days of the flowering period. With a single artificial pollination, we obtained higher fruit set with pollination on the fifth day (46.2%) than with pollination on the second day (24.0%). The soluble solid concentration in berry juice was higher in fruit with pollination on the fifth day. We also found it useful to use pollen from Vitis cultivars with artificial pollination to obtain a high percentage of fruit set in Vitis coignetiae Pulliat.