A method for producing a polyamine is described that provides excellent safety, a lot of flexibility regarding a variety of its productions, and that can produce a polyamine of high-molecular weight easily and inexpensively.The polyamine includes a combination of units of formula (1) or (2): —(NH—(CH2)m—NH—(CH2)n)—  (1) (in the formula (1), independently in every unit, “m” indicates an integral number of 0 or more and “n” indicates an integral number of 3 or more.) —(NH—y—NH —Z)—  (2) (in the formula (2), independently in every unit, “Y” and “Z” are the same as or different from each other, and they indicate substituted or unsubstituted groups including unsaturated aliphatic, cyclic aliphatic or aromatic hydrocarbon radicals that can include hetero atoms.).