A spectroscopic device includes a lamp house accommodating a light source inside, a spectrometer configured to disperse light from the lamp house, a temperature measurement means for measuring a temperature of the spectrometer, a heating means for heating the spectrometer, a storage means and a control unit. The storage means stores the detection temperature of the temperature measurement means at a time when an optical axis is stable in the spectrometer in a state where the light source is illuminated. The control unit is configured to control operation of the heating means, and to cause the heating means to operate, when the light source is illuminated from a light-off state, until a detection temperature of the temperature measurement means reaches the detection temperature stored in the storage means.