WE CLAIM:
[Claim 1]
A polyamide fiber which has a single fiber fineness of less than 5 dtex, and has a stress per unit fineness of 0.7 cN/dtex or more in 3% elongation in a tensile test of the fiber,
wherein a stress F1 in 3% elongation in a tensile test of the fiber before 100°C boiling water treatment and a stress F2 in 3% elongation in a tensile test of the fiber after the treatment satisfy the following formula (1):
F2/F1 > 0.7 (1).
[Claim 2]
The polyamide fiber according to claim 1, wherein the polyamide fiber has a stress per unit fineness of 2.0 cN/dtex or more in 15% elongation in a tensile test of the fiber, and a stress P1 in 15% elongation in a tensile test of the fiber before 100°C boiling water treatment and a stress P2 in 15% elongation in a tensile test of the fiber after the treatment satisfy the following formula (2):
P2/P1 > 0.8 (2).
[Claim 3]
The polyamide fiber according to claim 1 or 2, wherein 50% by mass or more of monomers constituting polyamide contained in the polyamide fiber is a biomass-derived monomer. [Claim 4]
A fabric comprising the polyamide fiber according to any one of claims 1 to 3.