At present a large number of herbicidal compositions have been developed and used. However weeds to be controlled include a lot of kinds and the emergence thereof extends over a long period of time. Therefore the appearance of a herbicidal composition having a broad weed spectrum and having a high activity and a long residual effect is desired. The present invention relates to a synergistic herbicidal composition comprising (A) at least one member selected from the group consisting of flazasulfuron nicosulfuron and their salts and (B) pyroxasulfone or its salt. According to the synergistic herbicidal composition of the present invention a herbicidal composition having a broad weed spectrum and having a high activity and a long residual effect can be provided.