A resonance circuit is interposed between a base and a collector of an oscillating transistor and is configured such that a resonance frequency is switched in correspondence with two different frequency bands. A first feedback unit is interposed between the base and an emitter of the oscillating transistor and a second feedback unit is interposed between the emitter and the collector of the oscillating transistor. One of the first feedback unit and the second feedback unit is configured by series-parallel connection of three reactive elements so as to exhibit one of inductive and capacitance characteristics in the two different frequency bands, and the other feedback unit is configured so as to exhibit the same characteristic as that of one feedback unit. As a result, oscillation is performed in the two frequency bands.