Abstract: Disclosed is an herbicidal composition containing: a pyrimidinedione-based compound as an active ingredient; and an efficacy enhancer. The herbicidal composition can increase biological effect expression characteristics of the pyrimidinedione-based composition as a contact herbicide, improve fast-acting property on monocot weeds as well as broadleaf weeds through enhanced spreading ability and penetrating power, and effectively control, at a low dose, even resistant weeds showing resistance to other herbicides. Furthermore, the herbicidal composition retains thermodynamic stability to increase storage stability, and can exhibit uniform and excellent efficacy at the time of chemical treatment through the uniform dispersion of the active ingredient.