An imidazolidinedione compound of the formula: ##STR1## wherein X is a chlorine atom or a bromine atom, Y is an oxygen atom or a sulfur atom, and R.sub.1 and R.sub.2 are each a C.sub.1 -C.sub.4 alkyl group, a C.sub.1 -C.sub.4 alkoxy group, a C.sub.1 -C.sub.4 alkylthio group, an ar(C.sub.1 -C.sub.4)alkylthio group, a C.sub.1 -C.sub.4 alkoxy(C.sub.2 -C.sub.4)alkoxy group, a phenyl group, a phenoxy group, a C.sub.1 -C.sub.4 alkylthiophenoxy group, a C.sub.1 -C.sub.8 alkylamino group, a C.sub.2 -C.sub.8 alkenylamino group or a cyano(C.sub.1 -C.sub.4)alkylamino group, which is useful as an agricultural chemical such as insecticides, acaricides, nematocides and/or fungicides with high safety to mammalian animals and human beings.