To provide a high-density optical interconnect device, information processing device and data transmission method which are able to suppress limitations caused by the widening of light beams and the size of lenses. An optical interconnect unit includes a plurality of first lenses and a plurality of second lenses corresponding to a plurality of light-emitting element groups, and a plurality of light beams emitted from the plurality of light-emitting element groups pass through plurality of first lenses and the plurality of second lenses. The optical interconnect unit also includes a plurality of third lenses and a plurality of fourth lenses, and light beam groups pass through any one of the plurality of third lenses and the plurality of fourth lenses, and are focused by any one of a plurality of light-receiving element groups that include a plurality of light-receiving elements.