[Object] To provide a light source device and imaging system capable of issuing a warning to a user in accordance with an actual deterioration state of a light source.[Solution] The light source device includes: at least one light source； a light monitor unit that detects emitted light emitted from the light source； a light source drive unit that controls a drive current or an applied voltage of the light source such that a detection value detected by the light monitor unit indicates a predetermined target value； and a warning unit that performs a primary warning when the drive current or the applied voltage of the light source reaches a predetermined reference value, and performs a predetermined process on a basis of a deterioration level of the light source after the primary warning is performed.
