A laser device comprising: an output unit ; and a light amplifying unit , wherein the output unit is configured to output seed light (L1) to the light amplifying unit , wherein the light amplifying unit is configured to amplify the seed light (L1), wherein the output unit comprises: a light source unit configured to output, as the seed light (L1), 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 (L1) 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 (L1) with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light (L1) 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 (L2) with respect to the intensity-time waveform of the seed light (L1) is suppressed. an output unit ; and a light amplifying unit , wherein the output unit is configured to output seed light (L1) to the light amplifying unit , wherein the light amplifying unit is configured to amplify the seed light (L1), wherein the output unit comprises: a light source unit configured to output, as the seed light (L1), 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 (L1) 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 (L1) with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light (L1) 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 (L2) with respect to the intensity-time waveform of the seed light (L1) is suppressed. a light source unit configured to output, as the seed light (L1), 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 (L1) 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 (L1) with a wavelength are gain of the light amplifying unit input to the light amplifying unit earlier than the components of the seed light (L1) 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 (L2) with respect to the intensity-time waveform of the seed light (L1) is suppressed. <EOS>