Abstract: The present invention relates to amidoxime derivatives of the formula (I): ##STR1## wherein R.sub.1 is a C.sub.1-3 alkyl or allyl group, a methyl group substituted by chlorine or fluorine atom or ethoxycarbonyl or diethyldithiophosphate group, a phenoxymethyl group unsubstituted or substituted by chlorine atom, a C.sub.2 alkoxy or phenoxy group unsubstituted or substituted by chlorine atom or ethoxycarbonylethoxy group, a phenyl group unsubstituted or substituted by chlorine or fluorine atom, a benzyl group unsubstituted or substituted by chlorine atom, or a morpholine group; R.sub.2 is a phenoxymethyl or phenoxyethyl group substituted by chlorine atom, a phenyl group substituted by chlorine atom or methoxy group, or an ethoxy group. The compounds of the invention have a extremely high selectivity between paddy rice or crop plants and weeds and a strong activity on weeds. Moreover, the compounds have a very low phytotoxicity to paddy rice and crop plants.