Various domain structures of Sb:Si(100) surfaces with a miscut of 2 degrees were observed, depending on the Sb coverage and substrate temperature. A single domain of 2 x 1 phase was observed after deposition of 0.5 ML of Sb at a substrate temperature of 375 K, and a single domain of 1 x 2 phase appears after annealing at 600 K the surface on which similar or equal to 2-6 ML of Sb had been deposited at a substrate temperature of 375 K. A double domain of 1 x 2 and 2 x 1 phases appeared after deposition of 0.9 ML of Sb at high substrate temperatures (650-1000 K) or upon annealing the 1 x 2 single domain above 800 K. Also, a c(4 x 4) phase appeared via a 2 x 2 phase after annealing the 1 x 2 surface. Surface mixing, anisotropic stress, and the elimination of the reformed bonding in the S-B step are expected to be the main causes of the observed domain structures and reconstructions.