To improve weather resistance and molecular characteristics of a polyamide and obtain the subject polyamide by carrying out polymerization or polycondensation of a polyamide-forming monomer in the presence of a specific piperidine and a specific phenol.

Polymerization or polycondensation of (A) a polyamide-forming monomer is carried out in the presence of (B) 0.02-0.7 wt.% 4-amino-2,2,6,6- tetraalkylpiperidine, (C) 0-0.5 wt.% aliphatic or alicyclic diamine having primary or tertiary amino group and (D) 0.02-0.7 wt.% 2,6-dialkylphenol represented by the formula (R1 and R2 are each a 1-6C alkyl; R3 is H or methyl; A is a free carboxyl group, etc.; when A is a primary amine, (x) is 2 and (y) is 1 or (x) is 2 and (y) is 1, etc.), and having OH group at fourth position, and each component is mutually supplemented so that total amount of the components A to D is 100%, and total amount of the components B to D is 0.05-1.3 and the components B to D is bonded through an amide bond to the polymer chain.