[Problem] To provide a 3D imaging optical system, 3D imaging device, and endoscope that are capable of 3D observations. [Solution] The 3D imaging optical system (1) is characterized by being provided, in sequence from the object side to the imaging plane side, with: a front group (Gf) having a first front group (Gf1) centered on a first front group center axis (C1) and a second front group (Gf2) centered on a second front group center axis (C2) parallel to the first front group center axis (C1)； a front deflection group (Gfd) disposed at the imaging plane side of the first front group (Gf1) and/or the second front group； and a back group (Gb) disposed at the imaging plane side of the front group (Gf) and the front deflection group (Gfd) and having a single back group center axis. The 3D imaging optical system (1) is further characterized in that a first light beam (L1) radiating from an object passes through at least the first front group (Gf1) and the back group (Gb) and enters the imaging plane (I), a second light beam (L2) radiating from the object passes through at least the second front group (Gf2) and the back group (Gb) and enters the imaging plane (I), the first light beam and/or the second light beam passes through the front deflection group, and the front deflection group (Gfd) deflects the first light beam (L1) and second light beam (L2) in a manner so as to cause same to have different orientations when projecting same at a cross section containing the back group center axis (Cb) and perpendicular to a plane containing the first front group center axis (C1) and second front group center axis (C2).Le problème décrit par la présente invention est d'obtenir un système optique d'imagerie 3D, un dispositif imageur 3D et un endoscope qui permettent de réaliser des observations 3D. La solution selon l'invention porte sur un système optique d'imagerie 3D (1) qui est caractérisé en ce qu'il comprend successivement, depuis le côté objet jusqu'au côté plan d'imager
