The La atomic wires were fabricated from La-2@C-80. After heating the single-walled carbon nanotubes encapsulating the La2@C-80, so-called nanopeapods, we obtained the atomic wires of La atoms inside carbon nanotubes (CNTs) and studied their structures by using high-resolution electron microscopy (HR-TEM) and electron energy loss spectroscopy (EELS). The La atoms form dimers and linearly arrange inside the CNTs. The valence state of the La in atomic wires is the same as that in the pristine La-2@C-80 peapods.