The preferred in the present invention among the 2-halomethyl-1,3,4-oxadiazole compounds are those having the following Formula [I]: ##STR1## wherein Z is a halogen atom such as a fluorine atom, chlorine atom or bromine atom, Y is a hydrogen atom, a halogen atom, an alkyl group or an aryl group, A is a heterocyclic radical, m is an integer of from 1 to 3, and n is an integer of 0 or 1.