PURPOSE: To achieve a temperature compensation type cavity resonator with simple construction and electrically stable and low cost, by providing an expansion and contraction absorbing section on the way of a cylinder of a resonator main body, and selecting the line expansion coefficient of the cylinder to a prescribed range.

CONSTITUTION: Around a circular base plate 1, an expansion and contraction suppression body 2 consisting of a plurality of poles made of material of a low expansion coefficient are implanted. An upper plate 4 of a TE111 mode cylindrical type cavity resonator main body 3 is fixed to the body 2, and movement toward resonance axis Y of the upper palte 4 is restricted. At the center of the plate 1, a plurality of pole shaped insertion bodies 5 made of a material of high expansion coefficient are implanted, a bottom plate 6 of the main body 3 is fixed on them and the plate 6 can be moved toward Y by temperature change. On the way of a cylinder 7 of the main body 3, an expansion and contraction absorbing section 6 consisting of a condutive bellows 8 is provided. By selecting the material as α2<α1<α3, where the line expansion coefficient of the cylinder 7, suppessing body 7, and insertion body 5 are respectively α1, α2, α3, the change in the resonance frequency at temperature change can be compensated.