Effects of Choline Chloride on growth and yields of sweet-potato cultivated with the single crop and after-barley crop were summarized as follows. 1. The greatest effect was obtained when the sprout-bases of sweet potato were soaked in the solution of Choline Chloride for 24 hours, while the optimum concentration of Choline Chloride was 32.3ppm in case of single crop and 31.1ppm in after barley crop respectively. 2. Choline Chloride restrained the growth of stem; the length shortened and the dry weight decreased. 3. The number of tubers and yields were increased by treating choline chloride. It may be thought that the translocations of assimilation substance from leaves and stem to tubers, was stimulated by treating choline chloride. The tendancy of higher yielding was shown in the early harvesting than in the usual harvesting 4. Sugar and starch content were higher, crude fiber and crude protein content were lower as compared with the control.