An optical beamforming device includes an RF front-end transmitting or receiving RF signals and an optical beamformer forming or compensating for a time delay for each of the plurality of channels based on the RF signals. The optical beamformer includes E/O converters converting the RF signals into optical signals, respectively, a linear modulator generating an optical modulation signal based on an RF input signal, a TTD array outputting an optical combined signal obtained by compensating for a time delay degree of the input optical signals or outputting output optical signals, in each of which a time delay is formed for each channel, by distributing the optical modulation signal, a photo detector generating an RF output signal to an RF back-end based on the optical combined signal, and O/E converters converting the output optical signals into RF signals, respectively.