According to one aspect of the present invention, there is provided a voltage controlled oscillator controlling frequency of an output signal according to input voltage, the voltage controlled oscillator including a current controlled oscillator setting the frequency of the output signal based on control current, and a voltage-current converter including a transistor controlling a current amount of the control current according to the input voltage, in which the voltage-current converter is supplied with control voltage, and threshold value voltage of the transistor is controlled according to the control voltage.