A local oscillator comprising: a frequency generator having a circuit coupling in ring-shape 2N voltage-controlled oscillators (1a, 1b, 1c, 1d), where N is an integer larger than or equal to 2, which are adapted to control oscillation frequencies by an input voltage, for outputting first and second sinusoidal signals by generating the first sinusoidal signals using outputs of even number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and generating the second sinusoidal signals having same frequencies and different phases as the first sinusoidal signals using outputs of odd number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators; a phase detector for outputting either a positive or a negative voltage depending on whether a phase difference between the first and second sinusoidal signals output from the frequency generator is greater than a reference phase difference; and a comparator for outputting a comparison result between a voltage output from the phase detector and a reference voltage, or a comparison result between the voltage output from the phase detector and a voltage obtained by inverting polarity of the voltage, wherein the frequency generator is adapted to control the phase of the first sinusoidal signal or that of the second sinusoidal signal so that the phase difference approaches the reference phase difference by using the comparison result output from the comparator, wherein the frequency generator is adapted to generate the first sinusoidal signal by multiplying sinusoidal signals output from each of the even number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and generates the second sinusoidal signal by multiplying sinusoidal signals output from each of the odd number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and wherein the frequency generator further comprises a phase-locked loop, PLL, adapted to control voltages input to the odd number-th voltage-controlled oscillators by outputting a direct current voltage on a basis of a comparison between a frequency obtained by dividing a frequency of a sinusoidal signal output from the odd number-th voltage-controlled oscillators and a frequency of a reference signal. a frequency generator having a circuit coupling in ring-shape 2N voltage-controlled oscillators (1a, 1b, 1c, 1d), where N is an integer larger than or equal to 2, which are adapted to control oscillation frequencies by an input voltage, for outputting first and second sinusoidal signals by generating the first sinusoidal signals using outputs of even number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and generating the second sinusoidal signals having same frequencies and different phases as the first sinusoidal signals using outputs of odd number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators; a phase detector for outputting either a positive or a negative voltage depending on whether a phase difference between the first and second sinusoidal signals output from the frequency generator is greater than a reference phase difference; and a comparator for outputting a comparison result between a voltage output from the phase detector and a reference voltage, or a comparison result between the voltage output from the phase detector and a voltage obtained by inverting polarity of the voltage, wherein the frequency generator is adapted to control the phase of the first sinusoidal signal or that of the second sinusoidal signal so that the phase difference approaches the reference phase difference by using the comparison result output from the comparator, wherein the frequency generator is adapted to generate the first sinusoidal signal by multiplying sinusoidal signals output from each of the even number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and generates the second sinusoidal signal by multiplying sinusoidal signals output from each of the odd number-th voltage-controlled oscillators included in the 2N voltage-controlled oscillators, and wherein the frequency generator further comprises a phase-locked loop, PLL, adapted to control voltages input to the odd number-th voltage-controlled oscillators by outputting a direct current voltage on a basis of a comparison between a frequency obtained by dividing a frequency of a sinusoidal signal output from the odd number-th voltage-controlled oscillators and a frequency of a reference signal.