In a medical-image observation apparatus, an image display-area display-control unit causes a display unit to display a main examination area for displaying a thumbnail of a medical image to be read, and an observation-image preparation area for displaying a thumbnail of a medical image selected as a medical image to be used for comparative image reading. After a reading-subject image display-control unit causes the display unit to display a thumbnail of a medical image to be read in the main examination area, upon receiving an operation of moving the medical image of which thumbnail is displayed in the main examination area into the observation-image preparation area, a comparison-subject image display-control unit specifies a medical image to be a comparison subject based on attribution information about the moved medical image, and causes the display unit to display a thumbnail of the specified medical image.