PURPOSE: To obtain a retaining construction of a foamed body in which the foamed body and a mating part are fixed securely while the tip of a screw is concealed into a projection, by engaging a screw with a plate nut inserted into the projection of the foamed body.

CONSTITUTION: A projection 13 protruded in the direction A of inserting a screw is previously formed integral at a screw retaining part 5 corresponding to a hole 3 for mounting a mating part 2 in a foamed body 12. When a plate nut 15 is inserted into the projection 13 from the direction B being guided with a guide section 14, a stopper 17 of the plate nut 15 hits the guide section 14 and a threaded hole 20 of the plate nut 15 is positioned at the center of the projection 13. A mating part 2 is put on an opposed surface 8 of the foamed body 12 and then, a screw 4 is inserted through the mounting hole 3 and engaged with the threaded hole 20 of the plate nut 15 to fix the part 2. As the thickness l1 of the screw retaining part 5 is larger than that l2 of the foaming body 12, the foaming body 12 can not be broken so easily. The tip 11 of the screw 4 is located in the projection 13, covered therewith 13 without being exposed outside.