The present invention provides a spin injection electrode structure, a spin transport element, and a spin transport device which enable effective spin injection in a silicon channel layer at room temperature. A spin injection electrode structure IE comprises a silicon channel layer 12, a first magnesium oxide film 13A disposed on a first part of the silicon channel layer 12, and a first ferromagnetic layer 14A disposed on the first magnesium oxide film 13A. The first magnesium oxide film 13A partly includes a first lattice-matched part P lattice-matched with both of the silicon channel layer 12 and the first ferromagnetic layer 14A.