The present invention relates to a light source apparatus that has a base structure capable of generating SC light and further having a structure that enables the shaping of the spectral waveform of the SC light, power adjustment of the SC light, or adjustment of the frequency of repetition of the pulse train that contains the SC light. For example, a light source apparatus that enables shaping of spectral waveforms comprises a seed light source that emits seed light which is a pulse train or continuous light; an optical fiber that generates SC light from the seed light, and spectrum shaping means for completely or partially changing the spectral waveform of the SC light. The shaping of the spectral waveform changes the maximum power of the seed light by changing the optical coupling efficiency of the seed light source and optical fiber, for example, thereby suitably deforms the spectrum of the SC light.