Six new alkaloids, broussonetines W, X, M1, U1, and J1 (1-6) were isolated from the branches of Broussonetia kazinoki SIEB. (Moraceae) as minor constituents. They were formulated as (2R,3R,4R,5R)-2-hydroxymethyl-3,4-dihydroxy-5-[7-(cyclohexy-2-on-1(6)-enyl) hyptel]pyrrolidine (1), (2R,3S,4R,5R)-2-hydroxymethyl-3-4dihydroxyl-5-[7-(cyclohexy-2-on-1(6)-rnyl) hrptyl]pyrrolidine-4-O-β-D-glucopyranoside (2), (2R,3R,4R,5R)-2-hy droxymethyl-3-4-dihydroxy-5-[(9R)-9,13-dihydroxytridecly]pyrrolidune (3), (2S,3S,4S)-2-hydroxymethyl-3-4-dihydoxy-5-(10-oxo-13-hydroxytridecyl)- 5-pyrroline (4), (2R)-2-{(1S,2S)-1,2-dihydroxy-8-[(2R,3R, 4R,5R)-5-(2-hydroxymethyl-3,4-dihydroxypyrrolidinyl)]octyl}piperidine (6).