PURPOSE: The titled novel coagulating agent, obtained by neutralizing a specific polyamine with hydrochloric acid, capable of exhibiting improved coagulating ability without using a salting out agent to give rubber products having improved quality without a bad influence of the salting out agent, and having improved economic efficiency, etc.

CONSTITUTION: A coagulating agent, consisting of an aqueous solution of a polyamine hydrochloride, and obtained by neutralizing (A) a polyamine, prepared by condensing (i) a polyethylene polyamine, e.g. ethylenediamine, with (ii) ethylene dichloride, and having 250W3,000 average molecular weight with (B) hydrochloric acid, and diluting the resultant neutralization product with water to 50wt% concentration. The molar ratio of the component (i) to the component (ii) is preferably (1:0.5)W(1:1.5) to give 250W3,000 average molecular weight of the component (A). Usually, a latex to be treated is preferably adjusted to 1.5W7pH with an acidic medium before the coagulation treatment.