A three-dimensional observation apparatus is provided which includes an optical reflection member which reflects a light beam and converges the light beam after the reflection, and image projectors for right and left eyes which project a medical image for the right and left eyes on the optical reflection member and forms an exit pupil for the right and left eyes at a position apart from the optical reflection member by a predetermined distance. The apparatus also includes a holding member which keeps a positional relationship of the image projector for the right eye to the optical reflection member and a positional relationship of the image projector for the left eye to the optical reflection member.