In the last report, the auther examined over the chemical conponents of water extracts derived from the bark of Maackia amurensis Rup. together with their pharmacological actions and came to a convulsions that there probably be contained in the bark of Maackia amurensis Rup. certain alkaloids which cause convulsions in mouse. This time, by using Dowex 50, cation exchange resine , the author has isolated a crystalline substance, m.p. 155°C., from the bark of Maackia amurensis. Examined with regard to physical properties and pharmacological action of the substance, following results has been obtained.