state the holding members 6 formed in the pushed in portion 5 and the holding members 6 formed on the inner peripheral coating body 24 are located so as to have the narrow spacing a therebetween within the space formed by the inner peripheral surface 14 of the core material 2 and to be opposed to each other next a manufacturing process for an automotive extrusion molded product in accordance with the present invention will be explained with reference to an embodiment shown in fig1 the synthetic resin core material 2 having a u shape in the cross section is extrusion molded in a first die 26 by using a first extruder 25 into which a hard synthetic resin is poured and the synthetic resin core material 2 is cooled by being caused to pass through a cooling tank 27 next the cut portions 7 8 having various shapes are punched out from the synthetic resin core material 2 having a u shape in the cross section by using a punching machine 28 and subsequently the synthetic resin core material 2 having the cut portions 7 8 is carried to a second die 29 in the second die 29 the coating body 3 the pushed in portion 5 connected to the coating body and holding members 6 projectingly provided at the outer periphery of the pushed in portion 5 are integrally extrusion molded on the synthetic resin core material 2 having the cut portions 7 8 by using a second extruder 30 into which a soft synthetic resin is.