A laser device connectable to an exposure apparatus includes a spectrometer configured to generate a measurement waveform from an interference pattern of laser light output from the laser device; and a processor configured to calculate a first spectral waveform indicating a relationship between a wavelength and a light intensity using the measurement waveform, calculate a representative waveform included in a wavelength range of the first spectral waveform, and calculate an evaluation value of the first spectral waveform using a first integration value obtained by integrating, over the wavelength range, a product of a function of a wavelength deviation from the representative wavelength and the light intensity.