To provide a low-cost semiconductor inertia sensor which requires no laser processing, is fit for high volume production, has a low parasitic capacitance, high sensitivity, high accuracy and excellent dimensional accuracy.

A first silicon wafer 21 is bonded to a second silicon wafer 22. The second silicon wafer 22 has a higher etching speed than that of the first silicon wafer 21 to a predetermined etchant. The first silicon wafer is ground to a predetermined thickness, thereby forming a single crystal silicon layer 24. After the single crystal silicon layer 24 is bonded to a glass substrate 10, the second silicon wafer is etched and removed. The remaining single crystal silicon layer is selectively etched and removed, whereby a semiconductor inertia sensor 30 having a pair of fixed electrodes 27, 28 of the single crystal silicon and bonded to the glass substrate and a movable electrode 26 of the single crystal silicon held between the fixed electrodes and floating over the glass substrate.