A wavelength-swept light source apparatus comprises a light source that emits a wavelength-swept light that varies in a predetermined cycle, a mode hop detector that detects a mode hop of the wavelength-swept light emitted from the light source； and a control unit that controls at least one of a parameter that defines a specified period having a predetermined fixed or variable time length provided in the predetermined cycle and a control parameter of the light source, thereby to set an occurrence timing of the mode hop detected by the mode hop detector outside of the specified period.
