A purpose of the observation system for surgical operation of the present invention is to sufficiently miniaturize a mirror while acquiring a three-dimensional image from two directions so as to prevent the mirror from impeding surgical work and monitor observation and reduce the burden on the surgeon, the observation system for surgical operation being provided with: a first imaging optical system for acquiring, from a first observation direction, a pair of optical images of a body to be imaged, the pair of optical images having parallax therebetween through a pair of openings arranged in parallel with each other； and a second imaging optical system for acquiring, from a second observation direction differing in optical axis angle from the first observation direction, another pair of optical images of a body to be imaged, the other pair of optical images having parallax through another pair of openings arranged in parallel with each other. The openings of the first imaging optical system are larger in area than the openings of the second imaging optical system, and the first imaging optical system and the second imaging optical system are arranged so as to satisfy the following conditional formula. 0.4 ≤ L2/L1 ≤ 0.6 (1) L1 is the distance between the centers of the openings of the first imaging optical system, and L2 is the distance between the centers of the openings of the second imaging optical system.La présente invention se rapporte à un système d'observation qui est destiné à une opération chirurgicale, et qui permet de miniaturiser suffisamment un miroir et d'obtenir une image tridimensionnelle en provenance de deux directions de manière à éviter que le miroir ne gêne l'intervention chirurgicale, à contrôler l'observation, et à faciliter le travail du chirurgien. Ce système d'observation destiné à une opération chirurgicale comprend : un premier système optique d'imagerie conçu pour obtenir, en provenance d'une première direction d'observation, une paire d'i
