A laser radar system, comprising: an optical oscillator to perform laser light oscillation; an optical modulator to modulate the laser light by oscillation of the optical oscillator; an optical antenna to emit the laser light modulated by the optical modulator into the atmosphere and to receive scattered light from an irradiated target as reception light; an optical receiver to perform heterodyne detection on the reception light received by the optical antenna; and a signal processor to calculate a spectrum of a reception signal obtained by the optical receiver's performing heterodyne detection, to decompose the spectrum using signal-to-noise ratios, and to calculate a velocity of the irradiated target from a decomposed spectrum, wherein the signal processor comprises: a range bin divider to divide the reception signal at intervals of a preset width of time gates; a Fourier transform processor to perform Fourier transform on a reception signal divided by the range bin divider and to calculate a spectrum of the reception signal for each of the time gates; an integrator to integrate spectrums calculated by the Fourier transform processor for each of the time gates; an SNR calculator to obtain a signal-to-noise ratio for a target distance from the spectrum integrated by the integrator; a number-of-decomposition setter to set the number of segments for the spectrum integrated by the integrator to be decomposed; a spectrum decomposer to decompose the spectrum integrated by the integrator by using the number of segments set by the number-of-decomposition setter and the signal-to-noise ratios calculated by the SNR calculator; and a wind velocity calculator to calculate a wind velocity of the irradiated target from a spectrum decomposed by the spectrum decomposer. an optical oscillator to perform laser light oscillation; an optical modulator to modulate the laser light by oscillation of the optical oscillator; an optical antenna to emit the laser light modulated by the optical modulator into the atmosphere and to receive scattered light from an irradiated target as reception light; an optical receiver to perform heterodyne detection on the reception light received by the optical antenna; and a signal processor to calculate a spectrum of a reception signal obtained by the optical receiver's performing heterodyne detection, to decompose the spectrum using signal-to-noise ratios, and to calculate a velocity of the irradiated target from a decomposed spectrum, wherein the signal processor comprises: a range bin divider to divide the reception signal at intervals of a preset width of time gates; a Fourier transform processor to perform Fourier transform on a reception signal divided by the range bin divider and to calculate a spectrum of the reception signal for each of the time gates; an integrator to integrate spectrums calculated by the Fourier transform processor for each of the time gates; an SNR calculator to obtain a signal-to-noise ratio for a target distance from the spectrum integrated by the integrator; a number-of-decomposition setter to set the number of segments for the spectrum integrated by the integrator to be decomposed; a spectrum decomposer to decompose the spectrum integrated by the integrator by using the number of segments set by the number-of-decomposition setter and the signal-to-noise ratios calculated by the SNR calculator; and a wind velocity calculator to calculate a wind velocity of the irradiated target from a spectrum decomposed by the spectrum decomposer. a range bin divider to divide the reception signal at intervals of a preset width of time gates; a Fourier transform processor to perform Fourier transform on a reception signal divided by the range bin divider and to calculate a spectrum of the reception signal for each of the time gates; an integrator to integrate spectrums calculated by the Fourier transform processor for each of the time gates; an SNR calculator to obtain a signal-to-noise ratio for a target distance from the spectrum integrated by the integrator; a number-of-decomposition setter to set the number of segments for the spectrum integrated by the integrator to be decomposed; a spectrum decomposer to decompose the spectrum integrated by the integrator by using the number of segments set by the number-of-decomposition setter and the signal-to-noise ratios calculated by the SNR calculator; and a wind velocity calculator to calculate a wind velocity of the irradiated target from a spectrum decomposed by the spectrum decomposer.