To provide an electrostatic capacitor-type sensor that does not require regulation such as zero-point adjustment and temperature compensation, etc. A pair of semi-circular differential electrodes are positioned next to each other in the vertical direction with a common electrode arranged so as to face the differential electrodes, with a fixed gap therebetween. The pair of differential electrodes and the common electrode are housed within an airtight container, and a dielectric fluid is sealed within the airtight container. The differential electrode on an upper side and the common electrode form an upper variable capacitor, and the differential electrode on the lower side and the common electrode form a lower variable capacitor.