A beam steering device includes an optical waveguide configured to split input light into a plurality of split light along a plurality of paths and output the plurality of split light to a plurality of output terminals which are aperiodically arranged, a plurality of phase shifters provided in the plurality of paths, wherein at least two phase shifters among the plurality of phase shifters have different phase delay length, and a signal input unit configured to supply a uniform signal to each of the plurality of phase shifters.