The varieties, Norin No. 1, Kokei No. 14 and Gifu No. 1 were used for sample of root tuber of sweet potatoes in this experiment. The cut fresh was cut in to 5 different weights and rooting were observed at the temperatures of 30°C and 35°C and with the moisture content of more than 85%, The results are follows: (1) The cut fresh forms a number of callus on its surface after 5-10 days and begins to germinate. In this case, the formation of callus on the cut fresh is closely related with the fibrobascular bundle. (2) The ratio of germinated buds at the callus was about 10% of that of root germination. (3) The author tried to cultivate the sweet potatoes by planting the cut freshes in the field. It was well-ascertained that the root tuber of sweet potatoes could be tuberized even by that method. (4) Although there are some problems for keeping freeping free from rotting, for promoting germination in case planting cut freshes from root tuber of sweet potatoes. But it is remarkable to be abls to sprout and root tuberize from the cut freshes on the direct planting method.