To provide implement a spin-polarized electron generating device having high spin polarization and high external quantum efficiency while allowing a certain degree of freedom in selecting materials of a substrate, a buffer layer, and a strained superlattice layer.In a spin-polarized electron generating device having a substrate, a buffer layer, and a strained superlattice layer formed on the buffer layer, an intermediate layer formed of a crystal having a lattice constant greater than that of a crystal used to form the buffer layer intervenes between the substrate and the buffer layer. With this arrangement, tensile strain causes cracks to be formed in the buffer layer in a direction perpendicular to the substrate, whereby the buffer layer has mosaic-like appearance. As a result, glide dislocations in an oblique direction do not propagate to the strained superlattice layer to be grown on the buffer layer, thereby improving crystallinity of the strained superlattice layer. Accordingly, spin polarization of excited electrons and external quantum efficiency of polarized electrons improve.