A utility part assembly includes a vehicular interior part and a utility part. The vehicular interior part has a first surface and a second surface that is opposite to the first surface and has a first mounting hole and a second mounting hole. The utility part includes a first member provided on the first surface and a second member provided on the second surface. The first member has a first coupling pin and one of a second coupling pin and a first coupling hole, and the second member has a coupling portion that is coupled to the first coupling pin and another one of the second coupling pin and the first coupling hole. The first coupling pin is inserted through the first mounting hole and coupled to the coupling portion, and the second coupling pin is inserted through the second mounting hole and coupled to the first coupling hole.