Tenebrio molitor beetles have been widely used in traditional and folklore medicines to treat various human diseases worldwide. Alzheimer’s disease (AD) is a neurodegenerative disorder and the most prevalent form of dementia in developed and developing countries. The human β-amyloid cleaving enzyme (BACE-1) is a target for AD treatments. This study was performed to determine BACE-1 inhibitory activity of 12 compounds that were extracted from T. molitor adults and their 65 related compounds using a fluorescence resonance energy transfer-based enzyme assay. The results were compared with those of two positive controls for BACE-1, the cell-permeable isophthalamide BACE-1 inhibitor IV and the natural BACE-1 inhibitor, epigallocatechin gallate (EGCG). Based on IC50 values, linoleic acid, ergosterol, palmitoleic acid, and tryptopol (28.41‒46.16 μM) were the most potent BACE-1 inhibitors and the anti-BACE-1 activity of these compounds was lower than either inhibitor IV (13.13 μM) or EGCG (1.12 μM). Multiple regression analysis of the anti-BACE-1 activities of compounds was examined using their IC50 values and the values of the physical parameters (molecular weight (MW), log P, and molecular refraction (MR)) for the 41 fatty acids (R2 = 0.674 (P = 0.044)) and 29 flavonoids (R2 = 0.587 (P = 0.063)). Correlation coefficient (r) analysis showed that MW, log P, and MR may be positively correlated with IC50 of the fatty acids (MW, r = 0.658; log P, r = 0.471; and MR, r = 0.713) and IC50 of the flavonoids (MW, r = 0.547; log P, r = 0.644; and MR, r = 0.591). Further studies will warrant possible applications of T. molitor adults as therapeutic BACE-1 blocker.