An optical grain evaluation device is provided with a light projection unit 58 for irradiating light from a light source onto grain a light reception unit 59 upon which light having passed through the grain is incident a grain evaluation unit 60 for evaluating the grain on the basis of information about the received light and a shielding part SH for isolating the area between the light source 50 and light projection unit 58 and the area between the light reception unit 59 and grain evaluation unit 60 so as to prevent light from the light projection unit 58 from directly striking the light reception unit 59. The area between the light source 50 and light projection unit 58 and the area between the light reception unit 59 and grain evaluation unit 60 are both configured such that the entirety of each area is an air propagation area in which light propagates through the air.
