Three new ent-kauran-type diterpenes (1–3), named arenterpenoids A–C, and five known ones (4–8) were isolated and identified from Arenga pinnata (Wurmb.) Merr. Fruits. The structures of these compounds were established by 1D and 2D NMR spectra and HR-ESI-MS. To the best of our knowledge, this is the first scientific report of diterpenes from Arenga genus.