To provide an electrostatic capacity type mechanical quantity sensor which is capable of preventing reductions in sensor performance due to the presence of gases in a closed space between a substrate and a movable electrode and avoiding large-size formation due to a gas-trap function and which keeps a pressure sensor integrated with an acceleration sensor.

A fixed electrode 14a for the pressure sensor and a fixed electrode 14b for the acceleration sensor are formed on a principal surface 11a of a first glass substrate 11. A silicon substrate 16 is joined onto the first glass substrate 11 in such a way that a pressure-sensitive diaphragm 16a may be arranged above the fixed electrode 14a and that a rocking member 16b may be arranged above the fixed electrode 14b. A second glass substrate 18 is joined onto the silicon substrate 16 in such a way as to envelop the rocking member 16b. A cavity 17a on the side of the pressure sensor communicates with cavities 17b and 17d on the side of the acceleration sensor.