High-purity stevioside sweeteners are being provided. Stevia Rebaudiana Bertoni varieties were identified using DNA analysis after cross and selective breeding were implemented. By crossing these varieties, a novel variety which enables continuous cultivation of the specific variety was developed (Deposition No. FERM BP-10870). Extracting the dried leaves of this variety assures consistent high-concentration of stevioside, which makes it possible to produce various favorable stevioside sweeteners.