The detailed crystal structure of cubic Li7La3Zr2O12 has been successfully determined by single-crystal X-ray structure analysis. The three-dimensional network of the Li-ion migration pathway with short Li-Li distance and occupational disordering is formed in the garnet-type framework structure. The basic unit of the pathway can be expressed as a loop constructed by the Li1 and Li2 sites. The loop links to another one, where only the Li1 site is shared by two loops as a junction.