PURPOSE: To obtain a higher polyamide excellent in flexibility, low-temperature impact resistance, etc., by feeding an aqueous solution containing a salt between adipic acid and a diamine selected from undecanediamine and dodecanediamine into a polymerization kettle and polymerizing the reaction mizture.

CONSTITUTION: A higher polyamide having undecamethylene adipamide units and/or dodecamethylene adipamide units as the principal structural units is obtained by feeding an aqueous solution containing at least 50wt% equimolar salt between at least one diamine selected from the group consisting of undecanediamine and dodecanediamine and adipic acid into a polymerization kettle and solution-polymerizing the solution at 240W300°C under elevated or atmospheric pressure.

EFFECT: The above diamine/adipic acid salt has a high solubility in water, so that an operation such as concentration, is unnecessary to feed a high concentration aqueous solution of the salt into a polymerization kettle. Besides, the polyamide thus produced is excellent also in resistance to flex fatigue and dimensional stability.