For the purpose of developing new antiseptics, we searched for compounds having high biocidal activity covering both gram-positive and gram-negative bacteria. Accordingly, we designed 1,5-disubstituted biguanides and synthesized them using two alternative efficient reaction schemes. The bactericidal activity of these biguanides was assayed by the micro titration plate method. Among the biguanides synthesized, 3,4 dichlorobenzyl derivatives were found to exhibit particularly high bactericidal activity. Ultimately, compound 11 was chosen as a candidate novel antiseptic, which is currently under continued evaluation.