e. An external force detecting sensor according to a third aspect of the present invention comprises a functional element including a supporter, a movable portion having a movable interdigitated electrode, rectangular in cross-section, coupled to the supporter via a beam, and fixed portion having a fixed interdigitated electrode, rectangular in cross-section, opposing the movable interdigitated electrode via a micro-gap; a supporting substrate for supporting the functional element; and a cap substrate mounted on the functional element from the o