disclosed is a 3 - propylaminobleomycin having low pulmonary toxicity , which expressed by the following general formula -- nh --. sub . 3 -- a --. sub . 4 -- b wherein represents a residue remaining after removing a hydroxyl group from the carboxyl group of bleomycinic acid , a represents a group of the formula ## str1 ## in which r 1 represents a hydrogen atom , an alkyl group having 1 to 10 carbon atoms , or a methyl which may be substituted by at least one of a phenyl group and a cycloalkyl group having 5 to 13 carbon atoms , said substituents being each optionally further substituted more than one position by one or more substituents selected from the class consisting of a halogen atom , a lower alkyl group having 1 to 4 carbon atoms , a lower alkoxy group having 1 to 4 carbon atoms , and benzyloxy group ; and r 2 represents a lower alkyl group having 1 to 4 carbon atoms or a benzyl group , b represents a group of the formula ## str2 ## in which r 3 and r 4 each represents a hydrogen atom , an alkyl group having 5 to 10 carbon atoms , or a methyl which may be substituted by at least one of a phenyl group and a cycloalkyl group , said substituents being each optionally further substituted more than one position by one or more substituents selected from the class consisting of a halogen atom , a lower alkyl group having 1 to 4 carbon atoms , a lower alkoxy group having 1 to 4 carbon atoms and a benzyloxy group , with the proviso that at least one of r 3 and r 4 is a group other than a hydrogen atom , and salt thereof .