A dynamic amount sensor has a detecting circuit that detects a change in an electrostatic capacitance of each of electrostatic capacitance elements comprised of a movable electrode and a fixed electrode. A switching circuit switches the detecting circuit to first and second connecting states that detect changes in the electrostatic capacitance of the electrostatic capacitance elements in accordance with a change in an attitude of the movable electrode in corresponding first and second detecting axes directions. In the first and second connecting states, the detecting circuit includes circuits formed by connecting the electrostatic capacitance elements in series which change electrostatic capacitances symmetrically along with inclination of the movable electrode in the corresponding first and second detecting axes directions. A carrier wave applying circuit applies carrier waves whose phases are inverted from each other by 180° to the electrostatic capacitance elements which are connected in series in the first and second connecting states of the detecting circuit.