The fruits of Cornus kousa Burg. were extracted with 80% aqueous MeOH, and the concentrated extract partitioned with EtOAc, n-BuOH and H$_2$O. Six lignans were isolated from the EtOAc fraction through repeated silica gel, ODS and Sephadex LH-20 column chromatographies. From the physico-chemical data, including NMR, MS and IR, the chemical structures of the compounds were determined to be (+)-pinoresinol (1), (-)-balanophonin (2), (+)-laricresinol(3), erythro-guaiacylglycerol-${eta}$-coniferyl aldehyde ether (4), threo-guaiacylglycerol-${eta}$-coniferyl aldehyde ether (5) and dihydrodehydrodiconiferyl alcohol (6), which were isolated for the first time from this plant. Most of these compounds showed cytotoxicity against human colon carci-noma (HCT-116) and human hepatocellular carcinoma (HepG2) cell lines in vitro, with IC$_{50}$ values ranging from 19.1 to 71.3 ${mu}$g/mL.