The present invention provides a method for controlling weeds in paddy rice cultivation, which comprises steps of: applying a water-diluted solution comprising a herbicidal compound such as 1-(2-chloro-6-propylimidazo[1,2-b]pyridazin-3-yslulfony)-3-(4,6-dimethoxypyrmidin-2-yl) urea to a paddy field and flooding the paddy field within the first week after the application of the herbicidal compound.
