A laser radar device comprising: a Light source to oscillate laser light in a continuous-wave manner or a quasi-continuous-wave manner; a frequency modulator to apply frequency modulation to the laser light oscillated by the Light source; a beam splitter to split the laser light modulated by the frequency modulator into transmission light and local oscillator light; a transmitting and receiving optics system to transmit the transmission light and to receive light reflected from a target; a receiver to receive the received light and the local oscillator light received by the transmitting and receiving optics system and to convert each of the received light and the local oscillator light into an electrical signal; and a receiving circuit to process the electrical signal converted by the receiver and to calculate distance information and speed information of the target, wherein the frequency modulation applied by the frequency modulator is modulation in which a stepwise change in which a frequency increases or decreases by a frequency difference F for each time width T is performed for at least one step, characterized in that: the frequency of the local oscillator is constant in a given time window, wherein the laser radar device includes a mechanism for separating frequency information resulting from a distance to a target and frequency information resulting from a speed of the target, wherein the receiving circuit divides a frequency difference between the local oscillator light and the received light by the frequency difference F, and determines a frequency difference corresponding to a remainder or a shortage as a Doppler frequency f d, wherein the frequency difference F in the stepwise change is sufficiently larger than the Doppler frequency due to movement of aerosol in the air. a Light source to oscillate laser light in a continuous-wave manner or a quasi-continuous-wave manner; a frequency modulator to apply frequency modulation to the laser light oscillated by the Light source; a beam splitter to split the laser light modulated by the frequency modulator into transmission light and local oscillator light; a transmitting and receiving optics system to transmit the transmission light and to receive light reflected from a target; a receiver to receive the received light and the local oscillator light received by the transmitting and receiving optics system and to convert each of the received light and the local oscillator light into an electrical signal; and a receiving circuit to process the electrical signal converted by the receiver and to calculate distance information and speed information of the target, wherein the frequency modulation applied by the frequency modulator is modulation in which a stepwise change in which a frequency increases or decreases by a frequency difference F for each time width T is performed for at least one step, characterized in that: the frequency of the local oscillator is constant in a given time window, wherein the laser radar device includes a mechanism for separating frequency information resulting from a distance to a target and frequency information resulting from a speed of the target, wherein the receiving circuit divides a frequency difference between the local oscillator light and the received light by the frequency difference F, and determines a frequency difference corresponding to a remainder or a shortage as a Doppler frequency f d, wherein the frequency difference F in the stepwise change is sufficiently larger than the Doppler frequency due to movement of aerosol in the air. the frequency of the local oscillator is constant in a given time window, wherein the laser radar device includes a mechanism for separating frequency information resulting from a distance to a target and frequency information resulting from a speed of the target, wherein the receiving circuit divides a frequency difference between the local oscillator light and the received light by the frequency difference F, and determines a frequency difference corresponding to a remainder or a shortage as a Doppler frequency f d, wherein the frequency difference F in the stepwise change is sufficiently larger than the Doppler frequency due to movement of aerosol in the air.