A new solvent system benzene-n-hexane-diethylamine (25 : 10 : 1), was found to show a good separation of cannabidiol, tetrahydrocannabinol and cannabinol in hemp resin by thin-layer chromatography, in which Rf-values of three constituents were 0.45, 0.35 and 0.25, respectively. Furthermore, the same solvent system was successfully applied to silica gel column chromatography for isolation of three constituents of hemp resin. Using cocaine hydrochloride as an internal standard of gas chromatography, relative retention times of cannabidiol, tetrahydrocannabinol and cannabinol were calculated to be 1.76, 2.34 and 2.88, respectively. Six kinds of hemps grown in India, U.S.A. and Japan, were quantitatively analyzed using gas chromatography, and against a common opinion, Japanese hemps were found to contain considerable amounts of tetrahydrocannabinol, a physiologically active constituent.