A 3D display device that includes: a first optical section of focal distance f1 provided with a group of small lenses arrayed along a specific direction; and a second optical section of focal distance f2 that converges N beams of parallel light that are emitted from the first optical section and hit the individual small lenses by converging so as to offset the N beams from an optical axis. A distance d1 between the first optical section and the second optical section satisfies f2−f1≦d1≦f2 and a viewing distance d2 from the second optical section satisfies d2≈f2.