Polyamide resin

A polyamide resin produced by polycondensation of a diamine component comprising 70 mol % or more of m-xylylenediamine and a dicarboxylic acid component comprising 70 mol % or more of a C4-C20 α, ω-straight-chain aliphatic dicarboxylic acid, wherein the polycondensation is performed in the presence of at least one phosphorus compound selected from the group consisting of phosphinic acid compounds and phosphonous acid compounds in an amount of 3 to 400 ppm in terms of phosphorus atom based on a theoretical yield amount of the polyamide resin and in the presence of an alkali metal compound of a weak acid having a dissociation constant lower than a first dissociation constant of a dicarboxylic acid mainly constituting the polyamide resin in an amount of 0.5 to 1.0 mol per one mole of the phosphorus compound, and wherein the polyamide resin satisfies the following requirements (A), (B) and (C):

• 14000≦a≦40000 (A) b≦1.000 (B) 0.9930<b−1.1a2×10−11+3.2a×10−7≦0.9980 (C)
• wherein a is a number average molecular weight calculated from the following formula:
• a=2×106/([COOH]+[NH2])
• wherein [COOH] is a terminal carboxyl concentration (μeq/g) and [NH2] is a terminal amino concentration (μeq/g),
• b is a terminal group molar ratio represented by the following formula:
• b=(1−18.015[NH2]−α([COOH]−[NH2]))/(1−18.015[NH2]+β([COOH]−[NH2]))
• wherein [COOH] and [NH2] are as defined above, α is Σ(Mna×na)/2 wherein Mna is a molecular weight of each dicarboxylic acid and na is a molar fraction of each carboxylic acid based on the total molar amount of the dicarboxylic acid component, and β is Σ(Mnb×nb)/2−18.015 wherein Mnb is a molecular weight of each diamine and nb is a molar fraction of each diamine based on the total molar amount of the diamine component.