A semiconductor-based beamforming antenna is provided. The beamforming antenna includes: a waveguide having a silicon medium formed between metal and forming a waveguide path; at least one diode array disposed in the waveguide, the at least one diode array being driven according to an applied electrical signal to reflect an incident signal by acting as a conductive reflecting wall; a radiator connected to the waveguide and radiating a beam corresponding to a signal reflected by the at least one diode array or an incident signal; and a feeder for supplying an electrical signal into the waveguide.