The reliability of a semiconductor device which has the semiconductor components which were mounted on the same surface of the same substrate via the bump electrodes with which height differs, and with which package structure differs is improved. Semiconductor component 2 of WPP structure is mounted on the main surface of the interposer substrate which forms a semiconductor device via a plurality of bump electrodes. Semiconductor component 3 of CSP structure is mounted on the main surface of an interposer substrate via a plurality of bump electrodes with larger diameter and contiguity pitch than the above-mentioned bump electrode. And under-filling 4a and 4b mutually different, are filled up between the facing surfaces of this interposer substrate and semiconductor components 2, and between the facing surfaces of the interposer substrate and semiconductor components 3, respectively.