Three new labdane diterpenes (1-3), together with eight known diterpenoids, were isolated from a methanol extract of the aerial parts of Aster spathulifolius. The structures of 1-3 were determined as (13R)-labda-7,14-diene 13-O-beta-d-(4'-O-acetyl)fucopyranoside (1), (13R)-labda-7,14-diene 13-O-beta-d-(3'-O-acetyl)fucopyranoside (2), and (13R)-labda-14(15)-en-8,13-diol 13-O-beta-d-fucopyranoside (3), on the basis of spectroscopic and chemical methods. Compounds 1, 2, and four of the known compounds exhibited generally nonspecific cytotoxicity against human A549, SK-OV-3, SK-MEL-2, XF498, and HCT15 tumor cells.