Provided is a three-dimensional-endoscope optical system that is provided with two objective optical systems having optical axes, which are arranged with a spacing therebetween, and that satisfies the following conditions:0.5 mm<；OP<；1.5 mm (1)；3 mm<；D<；200 mm (2)；α<；10° (3)； and110°<；ω<；180° (4),where OP is a spacing between the optical axes of optical members at the most distal ends of the objective optical systems, D is a depth of field, α is an angle of convergence (inward angle) of the depth of field D when performing near-point observation, and ω is an angle of view of the objective optical systems.
