A medical three-dimensional observation apparatus includes at least a pair of imaging units, a three-dimensional image processing unit, a calculating unit, and an index superimposing unit. The imaging units image a .specimen from different viewpoints. The three-dimensional image processing unit displays a three-dimensional image of the specimen on a display in accordance with images of the specimen. The calculating unit calculates a region of a three-dimensional reproduction space of the display in which the three-dimensional image of the specimen is to be reproduced. The index superimposing unit superimposes an annotation image on a depth position corresponding to the region in which the three-dimensional image is reproduced.
