A high-frequency oscillation circuit in accordance with the present invention includes an resonance circuit for generating oscillation frequency signal; an amplifying means having an input port for receiving the signal originating from the resonance; and inductive element having one port connected to the output port of the amplifying means; an T-shape matching element or strip line; a capacitive element connected to the other port of the inductive element or the T-shape matching element or one port of the strip line; wherein the input part of the amplifying means is connected to the connection point of the inductive element or T-shape matching element and the capacitive element or T-shape matching element or strip line and the capacitor match the impedances of both sides of the amplifying means and form low pass filter so that the harmonic components included in the output of the amplifying means can be removed, and construct a resonance circuit so that the frequency selectively Q is improved and then the signal-to-noise ratio can be improved.