PURPOSE: To detect highly precisely accelerations in three directions of vertical, lateral and longitudinal axes of a sensor.

CONSTITUTION: A movable electrode 30 is supported between silicon bases 21 and 22 with a support frame 29 and support beams 31 interposed. On the opposed surfaces of the silicon bases 21 and 22, rectangular fixed electrodes 25 and 26, and 27 and 28, are formed by sixs respectively. Four through holes 32 are bored in the movable electrode 60 and remaining movable electrode parts 33 have equal separation distances to and equal effective areas for the aforesaid fixed electrodes 25, 26, 27 and 28 respectively. With displacement of the separation distances and the effective areas, capacitance changes and accelerations in directions of three axes are detected.