A laser device, comprising: a light source configured to emit light; a first reflector configured to reflect the light toward a scanning region ; a second reflector configured to reflect the light reflected from the scanning region ; a light receiver configured to receive the light reflected by the second reflector ; a driver configured to swing the first and the second reflectors in an angular range (α) corresponding to the scanning region ; and a calculator that is configured to: store first information about the light reflected by the first reflector toward scanning region and second information about the light received by the light receiver , and measure movement speed and movement direction of a target reflecting the light from the first reflector based on the first and the second information, characterized in that the laser device further comprises a controller configured to control an amount of the light emitted from the light source based on the movement speed and the movement direction of the target, wherein a partition wall is provided between the first reflector and the second reflector for preventing the light emitted from the first reflector from directly wrapping around the second reflector , wherein the laser device further comprises a fixed mirror and the partition wall has a through hole , the fixed mirror and the through hole being arranged so that one part of the light emitted from the first reflector is guided to a light sensor via the through hole after being reflected by the fixed mirror , and wherein the emission intensity of the light emitted from the light source is monitored by means of the fixed mirror , the light sensor and the controller , the electric signal from the light sensor being fed back to the controller . a light source configured to emit light; a first reflector configured to reflect the light toward a scanning region ; a second reflector configured to reflect the light reflected from the scanning region ; a light receiver configured to receive the light reflected by the second reflector ; a driver configured to swing the first and the second reflectors in an angular range (α) corresponding to the scanning region ; and a calculator that is configured to: store first information about the light reflected by the first reflector toward scanning region and second information about the light received by the light receiver , and measure movement speed and movement direction of a target reflecting the light from the first reflector based on the first and the second information, store first information about the light reflected by the first reflector toward scanning region and second information about the light received by the light receiver , and measure movement speed and movement direction of a target reflecting the light from the first reflector based on the first and the second information, the laser device further comprises a controller configured to control an amount of the light emitted from the light source based on the movement speed and the movement direction of the target, wherein a partition wall is provided between the first reflector and the second reflector for preventing the light emitted from the first reflector from directly wrapping around the second reflector , wherein the laser device further comprises a fixed mirror and the partition wall has a through hole , the fixed mirror and the through hole being arranged so that one part of the light emitted from the first reflector is guided to a light sensor via the through hole after being reflected by the fixed mirror , and wherein the emission intensity of the light emitted from the light source is monitored by means of the fixed mirror , the light sensor and the controller , the electric signal from the light sensor being fed back to the controller . <EOS>