Polyamide production method

A method of producing a polyamide comprising (i) polycondensating a polyamide precursor containing a salt made from a dicarboxylic acid and a diamine under pressure in a pre-polymerization tank to obtain a prepolymer, and (ii) highly polymerizing the prepolymer with an extruder,

• wherein, when the prepolymer in a molten state in (i) is fed by a pump to the extruder having lower pressure than the pre-polymerization tank through a discharge side pipe disposed downstream of the pump, the prepolymer is fed such that length L [cm] of the discharge side pipe and linear velocity of discharge v [cm/s] of the prepolymer by the pump satisfy 0.1[s]≦L/v<10[s], and
• wherein a difference ΔP between a pressure (P1) of the pre-polymerization tank and a pressure (P2) of the extruder satisfies 0.3 MPa ≦ΔP<10 MPa.