Aspergillus luchuensis is widely used as a starter of saccharification in the koji industry, but no secondary metabolites have been reported from this fungus. Herein, we report the isolation and identification of four new diketopiperazine derivatives (1-4), one new methyl 4-(3-acetyl-2, 6-dihydroxyphenyl)-2-methoxybutanoate (5), and six known compounds (6-11) from the rice koji of A. luchuensis. The structures of 1-5 were determined by extensive spectral analysis including 1D and 2D NMR, HRESIMS, and CD, and ECD calculation. In antioxidant assays, compound 10 displayed moderate DPPH scavenging activity with an EC