Photodetectors　based　on　two-dimensional　materials　have　shown　impressive　performance　including　fast　and　broadband　photoresponse　and　high　responsivity.　However,　their　polarization　sensitivity　remains　to　be　improved.　Here,　we　propose　an　antimonene　photodetector　having　a　strong　polarization　sensitivity　with　a　broadband　photoresponse,　based　on　quantum　transport　calculations.　A　robust　photocurrent　is　generated　for　almost　the　whole　visible　range　under　small　bias,　and　it　saturates　at　a　small　bias　voltage　for　most　of　the　photon　energies.　The　photocurrent　shows　a　perfect　cosine　dependence　on　the　polarization　angle,　which　originates　from　a　second-order　response　to　the　electric　field　of　the　light.　This　leads　to　a　strong　polarization　sensitivity　to　the　linearly　polarized　light　with　a　large　extinction　ratio.　For　a　higher　photon　energy　around　3.2　eV,　a　rather　high　extinction　ratio　greater　than　100　can　be　achieved　along　with　a　larger　photocurrent.　Moreover,　there　is　an　evident　anisotropy　between　the　armchair　and　zigzag　directions,　as　the　photocurrent　intensity　in　the　zigzag　direction　can　be　approximately　17　times　larger　than　that　in　the　armchair　direction　at　a　small　bias.　These　results　suggest　that　antimonene　is　a　promising　candidate　for　anisotropic　photodetection　in　the　visible　range　especially　for　high　frequency　visible　light.