In search of small dielectric constant (D-k) and low-dissipation (D-f) energy substrates for high-frequency appliances, a benzoate-group-substituted bisphenol A based resin was synthesized from bisphenol A dibenzolate and bisphenol A diglycidyl ether. Compared to the common bisphenol A diglycidyl ether epoxy resin, introduction of the benzoate group was considered to lead to increased hydrophobic character, which was supported by water absorption investigation as well as absorption peak investigation of the OH region via Fourier transform infrared spectra. The cured resin with few water molecules exhibited restricted motion of the segment, and, consequently, thermally stable properties (coefficient of thermal expansion and thermogravimetric analysis) were achieved. Ultimately, the developed epoxy resin showed dramatically reduced D-k (3.05 at 1 GHz) and D-f (0.016 at 1 GHz) values as well as enhanced adhesive properties. The excellent overall properties lead to its promising use in various fields involving electrical devices.