A composite fiber is described which comprises a polyester component and a polyamide component bound in a side-by-side or eccentric core-in-sheath structure, exhibiting a percentage of crimp DC of 1.3-15.0% after the composite fiber is treated in boiling water for 30 minutes under a load of 1.76×10−3 cN/dtex, and then dry heat treated for 30 minutes at 100° C. under a load of 1.76×10−3 cN/dtex, for stabilization of the crimps and further dry heat treated for one minute at 160° C. under a load of 1.76×10−3 cN/dtex, as well as a percentage of crimp HC of 0.5-10% after immersion in water at 20-30° C. for 10 hours, and a difference ΔC of 0.5-7.0% between the percentage of crimps.