Problem to be solved: to provide a light source device capable of maintaining a color balance, a medical observation system, an illumination method and a program even when the light from each light emitting device is multiplexed on an optical path.The light source device 3 comprisesWhite wavelength band or at least redA first light source section 301 emitting first light including one or more wavelength bands of green and blueA second light source 305 which emits a second light containing a particular wavelength band included in the first light andA first detector 304 for detecting the light quantity of light in a particular wavelength band of the first light andThe first optical member 303 which combines the light of the wavelength band different from the particular wavelength band and the second light in the first light andEquipped withThe light source control unit 309 is based on the detection result of the first detectorThe first light source section 301 is controlled.Diagram【課題】各発光素子からの光を光路上で合波する場合であっても、カラーバランスを維持することができる光源装置、医療用観察システム、照明方法およびプログラムを提供する。【解決手段】光源装置３は、白色の波長帯域または少なくとも赤色、緑色および青色の１つ以上の波長帯域を含む第１の光を出射する第１の光源部３０１と、第１の光に含まれる特定の波長帯域を含む第２の光を出射する第２の光源部３０５と、第１の光のうち特定の波長帯域の光の光量を検出する第１の検出部３０４と、第１の光のうち特定の波長帯域とは異なる波長帯域の光と第２の光とを合波する第１の光学部材３０３と、を備え、光源制御部３０９が第１の検出部３０４の検出結果に基づいて、第１の光源部３０１を制御する。【選択図】図２
