1. A three-dimensional observation system comprising: image pickup means for picking up two images of an object of observation which have a parallax with respect to the object of observation; image display means for displaying the two images of the object of observation captured by the image pickup means so as to be observed as a three-dimensional image by an observer; light splitting means for splitting light representing the three-dimensional image emitted from the image display means; and optical means for guiding one of the lights representing the three-dimensional image split by the light spitting means to a position in front of the left and right eyes of a first observer who is squarely facing the object of observation, so that the parallax direction of the two images of the object of observation and the parallax direction of the first observer squarely facing the object of observation coincide, and guiding the other of the lights representing the three-dimensional image split by the light splitting means to a position in front of the left and right eyes of a second observer positioned squarely facing the object of observation from a direction different than the first observer, so that the parallax direction of the two images of the object of observation and the parallax direction of the second observer coincide.