The phenotypic performances have formed the basis for genetic purity evaluation. However, the phenotypic based the genetic purity assessment are time-consuming, expensive, and not stable due to a great environmental effect on traits expression. While, the genotypic based genetic purity evaluation of a variety offers an efficient, more stable, and precise result than those phenotypic method due to no environmental factors involved. The objectives of this study were to determine genetic purity and population structure of Granola L. potato variety derived from twelve collection sources using microsatellite markers. This study consisted of following steps, such as cultivation of Granola L. potato varieties in the field, DNA isolation, PCR analysis, amplified DNA fragment analysis. The results showed that Granola L. variety derived from twelve sources had high level of genetic purity which indicated by genetic similarity value of 0.96 observed in present study. Based on population structure analysis, Granola L. variety might have consisted of two sub-populations of which one sub-population was more dominant than other sub-population. Therefore, genetic purification activities for Granola L. variety are still needed to increase genetic purity and to reduce phenotypic differences in future.