This study was conducted to develop a simple, rapid, and reliable method for in vitro propagation of disease-free and true-to-type clones from sucker explants of thornless blackberry (Rubus fruticosus L. × R. parvifolius L.). To induce multiple shoots, the sucker explants were sterilized in 1% NaOCl solution, and then were aseptically cultured on the full and 1/2 MS solid medium supplemented with BAP (0.1, 0.5, 1.0, 2.0 mg/L). After six weeks of culture, the highest frequency (85.4%) of shoot formation from sucker explants was obtained on the full-strength MS medium with 1.0 mg/L BAP. Node explants obtained from multiple shoots were cultured on the various media of full- or half-strength of AD, B5, MS, SH, QL, WPM media, respectively. After 30 days of culture, plant growth was good on the half-AD, half-QL medium. After 90 days of culture, plant growth was good on the full MS and full SH medium. The survival rate of the plantlets after transfer to plastic pots containing soil mixture (sand: soil: vermiculite was 1:1:1, vol.) in the greenhouse was 98%. The results indicate that a multiple-shoot procedure can be applied for an efficient mass propagation of Rubus fruticosus L. × R. parvifolius L.