The invention provides N-phenyltetrahydrophthalamic acid derivatives represented by the general formula [I], methods of producing the same, herbicides containing the same as the effective components, imidoylchloride derivatives as the intermediate products and methods of producing the same, wherein X and Y each individually represent hydrogen atoms or halogen atoms, R1 represents a lower alkoxycarbonylalkylthio group, R2 represents a lower alkyl group, a halogenated lower alkyl group or a substituted or unsubstituted phenyl group, and R3 represents a lower alkoxy group, a lower alkenyloxy group, a lower alkynyloxy group, or a lower alkoxyalkoxy group. The herbicides of the present invention, which are very useful, can be widely applied to upland, paddy field, orchard, turf, forest, non-crop land, etc., and are not harmful to crops.