Disclosed is a ceramic trimmer capacitor comprising a ceramic board having a substantially semi-circular stator electrode formed on one surface thereof, which is pressed and gripped between a rotor member composed of a metal and an insulating frame, wherein a plurality of arcuate convex portions are formed on the frame on the surface thereof having abutting contact with the ceramic board so that the periphery of the rotor member is supported by the arcuate convex portions. In this ceramic trimmer capacitor, the reliability of the stability against cracking of the ceramic board and the dependency characteristic of the electrostatic capacitance on the rotor load are highly improved.