To provide a production method deactivating the remaining radical initiator in graft polymerization.

There are provided a method for producing a modified polyolefin resin, wherein the raw materials used in graft polymerization are (a), (b) and at least one component selected from (c), (d) and (e), while the method uses a continuous production machine selected from a single screw extruder and a twin screw extruder, and at least one cylinder kept at ≥235°C is included in cylinders used after kneading all raw materials used in the graft polymerization; and/or a method for producing a modified polyolefin resin, wherein the raw materials used in graft polymerization are (a), (b) and at least one component selected from (c), (d) and (e), while the method for producing a modified polyolefin resin uses a batch kneader selected from a Banbury mixer, a mill, a kneader and a heating roll, and the time of keeping the kneader temperature at ≥235°C after feeding all raw materials used in the graft polymerization to the kneader to be reacted is ≥10 s. The raw materials are as following: (a) 100 pts.wt. of polyolefin resin; (b) 0.01-5 pts.wt.of a radical polymerization initiator; (c) 0.01-10 pts.wt. of an epoxy group-containing vinyl monomer; (d) 0.01-10 pts.wt. of a monomer containing an ethylenic double bond and Si in the same molecule; and (e) 0.01-10 pts.wt. of a monomer containing an ethylenic double bond and an acidic polar group in the same molecule.