In order to breed the useful mutants in black raspberry, cultivated in Gochang-gun, leaf-petiol explants from shoot-proliferating culture was regenerated after irradiated with 30, 50 and 70 Gy gamma-ray. The LD50 dose of leaf-petiol explants was identified as 30Gy after two months. Morphological characteristics of the variants were observed such as stem variation, existence and nonexistence of spine, spine color, anthocyanin content, width of leaf, thick of leaf compared with donor cultivar. Of the 701 mutants, 14 lines with the useful mutant characters were selected and random amplified polymorphic DNA(RAPD) was carried out to confirm mutation state at the molecular level with 20 primers. There are many bands be revealed only in mutants and disappear in mutants reversely. RAPD analysis revealed a high level of genetic diversity among Control and mutants. Compared to Control, No. 14 mutant showed the highest genetic diversity. Also, the co-dominant SSR markers have allowed the evaluation of heterozygosity. Valuable mutants obtained will be useful for developing new cultivars and studying gene function in molecular level.