The preparation of single-phase with delafossite-type structure by means of the solid-state reaction method was investigated using X-ray diffraction. The results showed that notwhistanding the fact that there was a trace of metallic copper, nearly single-phase was obtained by using as a lanthanum source and by firing the mixed powder with nonstoichiometric composition ratio of in a vacuum at 1273 K for 10 h. The measurement of electrical conductivity and Seebeck coefficient showed that thus obtained was a p-type semiconductor and had a Seebeck coefficient of approximately .