To provide a herbicidal composition and a method for its application, whereby the effect of a herbicidally active ingredient is improved to reduce the environmental load on a site where the herbicide is applied or the periphery thereof, more than ever, and its dose can be reduced.A herbicidal composition comprising (1) a compound represented by the formula (I) or its salt: where T and Z are as defined in the specification, and (2) a polyoxyalkylene alkyl ether phosphate or its salt. A method for controlling undesired plants or inhibiting their growth, by applying the herbicidal composition.