PROBLEM TO BE SOLVED: To generate an image suitable for observation. SOLUTION: A medical light source device 100 emits light in one frame period including an exposure period in which all horizontal lines of a light emitting element 31 and a rolling shutter type image pickup device 521 are simultaneously exposed and a read-out period of the image pickup element 521. It includes a control value determining unit 972 that determines a light source control value indicating a target value of the light emitting amount of the element 31, and a light emitting control unit 973 that causes the light emitting element 31 to emit light with a light source controlling value corresponding to the light source control value. The light emitting control unit 973 turns off the light emitting element 31 in the reading period when the light source control value decreases from the first value to the second value while the light emitting element 31 is lit in the reading period, and in the reading period. When the light source control value increases from a third value different from the second value to a fourth value while the light emitting element 31 is turned off, the light emitting element 31 is turned on during the readout period. [Selection diagram] Fig. 2【課題】観察に適した画像の生成を可能とすること。【解決手段】医療用光源装置１００は、発光素子３１と、ローリングシャッタ方式の撮像素子５２１の全ての水平ラインが同時に露光される露光期間と撮像素子５２１の読み出し期間とを含む１フレーム期間における発光素子３１の発光量の目標値を示す光源制御値を決定する制御値決定部９７２と、光源制御値に応じた発光量で発光素子３１を発光させる発光制御部９７３とを備える。発光制御部９７３は、読み出し期間において発光素子３１を点灯させている状態で光源制御値が第１の値から第２の値に減少した場合に読み出し期間において発光素子３１を消灯させ、読み出し期間において発光素子３１を消灯させている状態で光源制御値が第２の値とは異なる第３の値から第４の値に増加した場合に、読み出し期間において発光素子３１を点灯させる。【選択図】図２
