A displacement amount monitoring electrode arrangement comprising a fixed electrode fixed with respect to a substrate and a movable electrode configured to be movable in a predetermined axis direction parallel to the substrate, each of which has a comb shape formed by a base portion (32-1, 34-1) and plural electrode fingers (32-2, 34-2) extending from the base portion (32-1, 34-1) in the predetermined axis direction, wherein said fixed electrode and said movable electrode are arranged such that the electrode fingers of the fixed electrode are engaged with the electrode fingers of the movable electrode, wherein the displacement amount monitoring electrode arrangement is configured to output a change amount (ΔC) of a capacitance between the fixed electrode and the movable electrode as a drive amount monitor signal usable for monitoring a displacement amount of a detection mass (16, 18) which is to be driven to have target amplitude, wherein the displacement amount monitoring electrode arrangement is configured such that there are at least one linear change region in which the change amount (ΔC) of the capacitance changes linearly with the displacement of the movable electrode in the predetermined axis direction, and at least one nonlinear change region in which the change amount (ΔC) of the capacitance changes nonlinearly with the displacement of the movable electrode in the predetermined axis direction, and wherein the displacement amount monitoring electrode arrangement is configured such that the nonlinear change region includes a characteristic in which a change sensitivity of the change amount (ΔC) of the capacitance with respect to the displacement amount of the movable electrode in the predetermined axis direction is greater than that in the linear change region, characterized in that the electrode fingers of the fixed electrode and the electrode fingers of the movable electrode are arranged to each other such that a target capacitance change amount of the capacitance corresponding to a target displacement amount of the displacement of the movable electrode in the predetermined axis direction, wherein the target displacement amount corresponds to the target amplitude to which the detection mass (16, 18) is to be driven, is in the nonlinear change region, wherein the displacement amount monitoring electrode arrangement has such dimensions that following formula is met: T m 1 d m 1 + T m 2 d m 2 ≦ S 1 d 1 d 1 − A 0 + S 2 d 2 d 2 − A 0 wherein A0 represents the target displacement amount; dm1 and dm2 represent spaced distances between the electrode fingers of the fixed electrode and the electrode fingers of the movable electrode in a direction perpendicular to the predetermined axis direction; Tm1 and Tm2 represent thicknesses of portions of the electrode fingers (32-2, 34-2) of the fixed electrode and the movable electrode which are spaced from and opposed to each other; S1 represents an area of portions of the electrode fingers of the fixed electrode which face the base portion of the movable electrode; S2 represents an area of portions of the electrode fingers of the movable electrode which face the base portion of the fixed electrode; d1 represents a distance between the base portion of the movable electrode and tip portions of the electrode fingers of the fixed electrode; and d2 represents a distance between the base portion of the fixed electrode and tip portions of the electrode fingers of the movable electrode.