A laser device comprising: an output unit; and a light amplifying unit, wherein the output unit is configured to output seed light to the light amplifying unit, wherein the light amplifying unit is configured to amplify the seed light, wherein the output unit comprises: a light source unit configured to output, as the seed light, a plurality of rays of light with a corresponding plurality of at least four different wavelength components (λ 1, λ 2, λ 3, λ 4) lying within a gain range of the light amplifying unit such that on each side of a peak of a gain of the light amplifying unit at least one of the wavelength components (λ 3; λ 2) is located; and f a seed light control unit configured to control an intensity-time waveform of the seed light output from the light source unit such that the components (λ 4, λ 3) more distant from the peak of the of the seed light with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light with a wavelength(λ 2 λ 2) closer to the peak of the gain of the light amplifying unit distortion of an intensity-time waveform of amplified light with respect to the intensity-time waveform of the seed light is suppressed. an output unit; and a light amplifying unit, wherein the output unit is configured to output seed light to the light amplifying unit, wherein the light amplifying unit is configured to amplify the seed light, wherein the output unit comprises: a light source unit configured to output, as the seed light, a plurality of rays of light with a corresponding plurality of at least four different wavelength components (λ 1, λ 2, λ 3, λ 4) lying within a gain range of the light amplifying unit such that on each side of a peak of a gain of the light amplifying unit at least one of the wavelength components (λ 3; λ 2) is located; and f a seed light control unit configured to control an intensity-time waveform of the seed light output from the light source unit such that the components (λ 4, λ 3) more distant from the peak of the of the seed light with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light with a wavelength(λ 2 λ 2) closer to the peak of the gain of the light amplifying unit distortion of an intensity-time waveform of amplified light with respect to the intensity-time waveform of the seed light is suppressed. a light source unit configured to output, as the seed light, a plurality of rays of light with a corresponding plurality of at least four different wavelength components (λ 1, λ 2, λ 3, λ 4) lying within a gain range of the light amplifying unit such that on each side of a peak of a gain of the light amplifying unit at least one of the wavelength components (λ 3; λ 2) is located; and f a seed light control unit configured to control an intensity-time waveform of the seed light output from the light source unit such that the components (λ 4, λ 3) more distant from the peak of the of the seed light with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light with a wavelength(λ 2 λ 2) closer to the peak of the gain of the light amplifying unit distortion of an intensity-time waveform of amplified light with respect to the intensity-time waveform of the seed light is suppressed.