Beam steering devices and optical apparatuses including the beam steering devices are provided. A beam steering device includes a light source configured to generate input lights having first different wavelengths, a multiplexer configured to simultaneously receive the generated input lights, and multiplex the received input lights into a multiplexed light, and an optical splitter configured to split the multiplexed light. The beam steering device further includes an optical modulator configured to modulate the split light, and an emitter configured to simultaneously emit output lights having second different wavelengths to different points arranged in a first direction, based on the modulated light.