Direct electrical detection of the binding of antibody and antigen of avian influenza virus was demonstrated through a biosensor derived from a double-gate FinFET. A simple detection method was employed in which the charge effect coming from the biomolecules was observed through the threshold voltage V-T shift. Due to the presence of a local backgate, the proposed device is individually addressable and the operating voltage is markedly low compared with similar nanowire-type biosensors. Furthermore, its unique structure allows for the channel to be immune to the noise from the biomolecules, which can be problematic for nanogap field-effect-transistor biosensors. The proposed device is complementary metal-oxide-semiconductor compatible and highly reproducible, and monolithic integration with the readout circuits is achievable. Hence, this approach provides a step toward the large-scale development of sensor chips for their potential use in medicine and biotechnology.