The polycondensation of phenyl 4-(octylamino)benzoate (1) proceeded in a chain-polymerization manner to yield aromatic polyamides with low polydispersities (M-W/M-n less than or equal to 1.1) even under normal conditions for step-growth polycondensation, in which initiator was not added. On the basis of the results of the polycondesations of 1 with initiator models, this self-initiated chain-growth polycondensation involves the formation of the dimer of 1, which initiates the chain-growth polymerization faster than step-growth polymerization.