PROBLEM TO BE SOLVED: To achieve the longevity of a light source lamp in an examination environment where turning on and off of a light source lamp is repeated highly frequently.SOLUTION: A light source device for an electronic endoscope includes a light source lamp (220) for supplying an illumination light to an endoscope body, a light source button (282) for receiving an instruction on turning on and off of the light source lamp, a light shielding mechanism (240) for shielding the illumination light supplied by the light source lamp, and a CPU (270) for executing a pseudo-turning off mode for maintaining a turning on state of the light source lamp for a certain time in a state that the illumination light from the light source lamp is shielded by the light shielding mechanism when a light source lamp turning off instruction is received on a predetermined condition.SELECTED DRAWING: Figure 1【課題】光源ランプの点灯／消灯が高頻度に繰り返される検査環境下において、光源ランプの長寿命化を実現すること。【解決手段】内視鏡本体に照明光を供給する光源ランプ（２２０）と、光源ランプの点灯／消灯指示を受け付ける光源ボタン（２８２）と、光源ランプが供給する照明光を遮光する遮光機構（２４０）と、所定条件下にて、光源ランプの消灯指示を受け付けた場合に遮光機構で光源ランプからの照明光を遮光した状態で光源ランプの点灯状態を一定時間維持する疑似消灯モードを実行するＣＰＵ（２７０）と、を有する構成とした。【選択図】図１
