In recent years, propolis has attracted much attention as an useful substance in medicine and functional food, even if it is known as a natural remedy in folk medicine since ancient times. propolis was registered as natural food since 1995 on Korean Food Act by Korean Food and Drug Administration(KFDA). The present study demonstrated the optimization of isolation of crude propolis by ethanol, and tumoricidal effect of pro polis. The optimal concentration of ethanol to separate a high quantity of propolis was $60\%$. The cytotoxic effect of ethanol extracted propolis against various cancer cell lines including murine lymphoma (Sarcoma-180), murine T-lymphoma (YAC-1), human breast carcinoma (MCF-7), human gastric carcinoma (KATOIII) and human hepatocellular carcinoma (Hep3B) and human lung adenocarcinoma (A-549) was observed using SRB and MIT assay. In order to investigate the curative activity by oral administration of propolis on tumor, ICR mice was subcutaneously implanted Sarcoma 180. In 300mg/kg and 600mg/kg propolis administered group, development of implanted tumors was inhibited by $40.9\%;and;67.9\%$ at 16th day, respectively. In the same dose of propolis administered group, development of implanted tumors was inhibited more strongly with dose dependent manner. Therefore, these data suggested propolis may show tumoricidal effects. In conclusion, these results indicate that propolis, one of the few natural remedies, can be used as functional food with tumoricidal effects.