To provide a compact voltage-controlled oscillator having excellent frequency characteristics.

A resonance section 1 of a voltage-controlled oscillator (VCO) comprises: variable capacitance elements 13 and 14 whose capacitance varies for adjusting a resonance frequency; and an inductance element 11. An emitter-grounded transistor 21 amplifies a frequency signal supplied from the resonance section 1 to a base terminal T1. A feedback section 2 including feedback capacitative elements 22 and 23 feeds back the frequency signal provided from an emitter terminal T2 of the transistor 21 to the transistor 21 through the base terminal T1. Base bleeder resistors R2 and R3, and the transistor 21 for adjusting a bias voltage applied to the base terminal T1 are formed in a common integrated circuit 3, and an emitter resistance R1 is provided outside of the integrated circuit 3 as an another body of a resistance element for adjusting an operating point of the transistor 21.