advance using the first resin material by injection molding or the like after that the second resin material not miscible with the first resin material is filled in the cavity of the cap 5 formed to close the opening of the container 4 thus the container 4 and the cap 5 are integrated with each other referring to fig2 for example when hips high impact polystyrene with a shrinkage factor of 0 4 to 0 7 is selected as the first resin material pp polypropylene with a shrinkage factor of 1 0 to 2 5 pa66 polyamide 66 with a shrinkage factor of 0 8 to 1 5 or the like which has a shrinkage factor larger than that of hips can be selected as the second resin material in this manner there are many combinations of resin materials having larger shrinkage factors than that of the first resin material this embodiment is merely an example and the present invention is not limited to this as described above in a composite molded product made of a large number of materials resin materials having larger shrinkage factors than that of the first resin material used to form the first member are selected to form the second and subsequent members when composite molding of integrating the first member and the second and subsequent members in the mold is performed the differences in shrinkage factor among the first resin material and the second and subsequent resin materials appear as differences in shrinkage amount this causes appropriate.