PROBLEM TO BE SOLVED: To provide a light source device, a medical observation system, a lighting method and a program capable of maintaining a color balance of white light in a case where each LED element emits light in synchronization with the vibration frequency of the vocal cords. A light source device 5 includes a light source control unit 59, and the light source control unit 59 has a first light source unit 51, a second light source unit 52, and a third light source unit before shifting to a strobe observation mode. The first detection is performed in a state where the light source 53 is made to emit light and a pulse current having a pulse width longer than a predetermined pulse width is applied to the first light source unit 51, the second light source unit 52, and the third light source unit 53. Based on the detection result detected by any one or more of the unit 55, the second detection unit 56, and the third detection unit 57, the first light source unit 51, the second light source unit 52, and the third light source unit A pulse current value at which the ratio of the amount of light emitted by the unit 53 is a predetermined ratio is set, and the transition to the strobe observation mode is performed while maintaining the pulse current value at the predetermined ratio. [Selection diagram] Fig. 2【課題】各ＬＥＤ素子を声帯の振動周波数に同期させて発光させる場合であって、白色光の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５は、光源制御部５９を備え、光源制御部５９は、ストロボ観察モードへ遷移させる前に、第１の光源部５１、第２の光源部５２および第３の光源部５３に発光させ、第１の光源部５１、第２の光源部５２および第３の光源部５３に所定のパルス幅よりも長いパルス幅のパルス電流を印加している状態において、第１の検出部５５、第２の検出部５６および第３の検出部５７のいずれか一つ１以上が検出した検出結果に基づいて、第１の光源部５１、第２の光源部５２および第３の光源部５３が発光する光の光量の比率が所定の比率となるパルス電流値を設定し、この所定の比率となるパルス電流値を維持しつつストロボ観察モードへ遷移させる。【選択図】図２
