An optical grain evaluation device is provided with: a light-projecting part 58 through which light from a light source is projected to grain; a light-receiving part 59 on which light transmitted through the grain is incident; a grain evaluation unit 60 configured to evaluate the grain based on information relating to the received light; and a shielding part SH that separates an area between the light source 50 and the light-projecting part 59 from an area between the light-receiving part 59 and the grain evaluation unit 60, and prevents light from the light-projecting part 58 from directly entering the light-receiving part 59. The area between the light source 50 and the light-projecting part 58, and the area between the light-receiving part 59 and the grain evaluation unit 60 are configured, over the entirety of the areas, as air transmission areas in which light is transmitted through air.