The thiadiazole compound represented by the formula (A): ##STR00001## wherein R.sup.1 represents a C1-C7 alkyl group, a C3-C7 alkenyl group, a C3-C7 alkynyl group and the like; R2 represents a C1-C4 alkyl group substituted with a hetero ring group in which the hetero ring group may be substituted, which the hetero ring group is a five-membered ring containing only an oxygen atom(s) or a sulfur atom(s) as a hetero atom(s); has an excellent arthropod pests controlling activity.