A pyrrole derivative having excellent anti-microbial activities is disclosed. This compound is represented by the following formula (I): ##STR1## wherein X.sub.1 and X.sub.2 are the same or different and mean individually a halogen atom, R.sub.1 denotes an alkyl, cycloalkyl, haloalkyl, alkenyl, substituted or unsubstituted phenyl, substituted or unsubstituted aralkyl group or a group --COR.sub.3 in which R.sub.3 is an alkyl group having at least five carbon atoms or a cycloalkyl, haloalkyl, alkenyl, substituted or unsubstituted phenyl, substituted or unsubstituted aralkyl, or heterocyclic group, and R.sub.2 stands for a hydrogen or halogen atom or an alkyl group, with a proviso that R.sub.1 is other than a hydrogen atom or methyl group when X.sub.1, X.sub.2 and R.sub.2 are each a bromine atom.