Polarization microscopic observation was carried out for solvent-cast films and solutions of multibranched polystyrenes. The multibranched polystyrenes were prepared by the radical polymerization of omega-methacryloyloxyethyl polystyrene macromonomers of different molecular weights. It was found that multibranched polystyrene, with long flexible polystyrene chains and without any mesogenic groups, form the mesomorphic phase depending on the branching architecture of the polymer molecule. The formation of the liquid crystalline phase indicates that the multibranched polystyrenes possessing large branch number and sufficient branch length behave as rod-like molecules. The large molecular anisotropy might be caused by the stretching of the backbone chain to maximize the conformational entropy of the individual flexible branch chains. The cast films of the multibranched polystyrene/linear polystyrene blend (50/50 by weight) showed the phase-separated structure of the mesomorphic domains dispersed in the isotropic matrix.