To provide a surgical microscope illumination structure which normally irradiates illumination light from an oblique direction, and is capable of irradiating a surgical field with the illumination light at an angle close to that of an optical axis of an objective optical system when necessary.SOLUTION: An auxiliary illumination device 16 is attached to a bottom surface of a microscope body 2 when necessary such that auxiliary illumination light B is reflected by a prism 30 at an auxiliary illumination angle θ2 smaller than an illumination angle θ1 of illumination light A toward a surgical field G, which makes it easier for the auxiliary illumination light B to reach a bottom of the surgical field G even when the surgical field is a deep cavity.SELECTED DRAWING: Figure 2【課題】通常時は照明光を斜め方向から照射し、必要時には照明光を対物光学系の光軸に近い角度で術野に照射することができる手術顕微鏡の照明構造を提供する。【解決手段】必要時には顕微鏡本体２の下面に補助照明装置１６を取付け、そのプリズム３０で補助照明光Ｂを反射して照明光Ａの照明角度θ１よりも小さい補助照明角度θ２で術野Ｇに向けて照射するため、深い穴状の術野Ｇの場合も底まで補助照明光Ｂを届かせやすい。【選択図】 図２
