PURPOSE: To obtain a composite resin containing molecular chains of polyamide and polyolefin entangled with each other and having excellent molding fluidity and physical properties, by carrying out the melting and kneading of a polyolefin with a polyamide simultaneous to the modification of the polyolefin in the presence of a specific modifying agent and an organic peroxide.

CONSTITUTION: 100pts.wt. of a mixture of (A) 50W95wt.%, preferably 60W90wt.% polyamide resin (e.g. nylon 6) having a relative viscosity of 1.5W5 and (B) 5W50wt.%, preferably 10W40wt.% polyolefin having a melt index of 0.05W50g/10min is compounded with (C) 0.02W5pts.wt., preferably 0.07W1pt.wt. of an α,β-unsaturated imide compound (e.g. N-cyclohexylmaleimide), (D) 0.01W3 pts.wt., preferably 0.05W0.8pt.wt. of an α,β-unsaturated carboxylic acid (anhy dride) compound (e.g. acrylic acid) and (E) 0.001W0.8pt.wt., preferably 0.008W0.2pt.wt. of an organic peroxide, and the mixture is kneaded under melt ing.