As well as achieving both downsizing and thickness reduction and sensitivity improvement of a semiconductor device that has: a MEMS sensor formed by bulk micromachining technique such as an acceleration sensor and an angular rate sensor; and an LSI circuit, a packaging structure of the semiconductor device having the MEMS sensor and the LSI circuit can be simplified. An integrated circuit having MISFETs and wirings is formed on a silicon layer of an SOI substrate, and the MEMS sensor containing a structure inside is formed by processing a substrate layer of the SOI substrate. In other words, by using both surfaces of the SOI substrate, the integrated circuit and the MEMS sensor are mounted on one SOI substrate. The integrated circuit and the MEMS sensor are electrically connected to each other by a through-electrode provided in the SOI substrate.