The present invention can provide a method having a high control effect on the removal of herbicide resistant weeds in a cultivation area for crops. The method includes a step of treating weeds with one or more of herbicides selected from the group consisting of saflufenacil, trifludimoxazin, flumioxazin, and ethyl [3-[2-chloro-4-fluoro-5-(1-methyl-6-trifluoromethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-3-yl)phenoxy]-2-pyridyloxy]acetate, wherein the herbicide resistant weeds are PPO-inhibitor resistant weeds having one or more mutations selected from the group consisting of an Arg128Met mutation, Arg128Gly mutation, Arg128His mutation, and Gly399Ala mutation in PPO.
