In view of obtaining potential anticancer compounds, we studied the inhibitory activity and the cytotoxic effects of a candidate compound in cancer cells. The cytotoxic effects of cannabidiol (CBD) in vitro were evaluated in NIH3T3 fibroblasts, B16 melanoma cells, A549 lung cancer cells, MDA-MB-231 breast cancer cells, Lenca kidney cells and SNU-C4 colon cancer cells. The cells were cultured in various concentrations of CBD for 48 h and 25 ${mu}$M of CBD for 6-36 h. The cells were observed to exhibit inhibitory effects of the cell viability in their growth, and then cytotoxicity was estimated. The inhibitory activity of CBD was increased in all cancer cells and showed especially strong increment in breast cancer cells. The cytotoxicity of CBD increased in a dose- and time-dependent manner with growth inhibition in all cancer cell lines. Also, to assess the membrane toxicity induced by CBD, we investigated lactate dehydrogenase (LDH) release. After treatment with various concentrations of CBD, LDH release rate of cancer cells was accelerated. On the other hand, in the induction of cell death, caspase-3, -8 and -9 activations were detected in cancer cells after treatment with various concentrations of CBD, and CBD effectively induced activity of caspase-3, -8 and -9 in A549 lung cancer cells, MDAMB-231 breast cancer cells and Renca kidney cells. Therefore these results suggest that CBD has a possibility of anticancer agents and anticancer effects against cancer cells by modulation of apoptotic pathway in the range of 5-80 ${mu}$M concentration.