PURPOSE: To realize a frequency-variable microwave resonance element wherein loss is little, frequency change width is larger, and temperature stability is excellent, by using a mechanical means capable of controlling electrically for changing the gap of two metal plates.

CONSTITUTION: A variable-capacitance element 5 whose capacitance is changed by changing the gap (d) between two parallel metal plates 4 and 4a by Δd with a mechanical means is used. The element 5 is combined with a low loss inductance element 3. Thereby a variable-frequency microwave resonance element wherein loss is little, frequency change width is large, and temperature stability is excellent can be obtained. A piezoelectric element or a magnetostriction element may be used as a mechanical means capable of controlling electrically for changing the gap of the metal plates.