PROBLEM TO BE SOLVED: To provide an optical evaluation device for grains having a light projector emitting light from a light source to the grains in storage state, the device being configured to reduce a problem in which the light transmitted through the grains directly enters a light receiver from the light projector, and thus reducing cost for manufacturing the light projector and the light receiver.SOLUTION: The present invention includes: a light projector 58 for emitting light from a light source 50 to grains； a light receiver 59 to which the light transmitted though grains is incident； a grain evaluating unit 60 for evaluating the grains on the basis of the received light information； and a shield SH that separates a region between the light source 50 and the light projector 58 and a region between the light receiver 59 and the grain evaluating unit 60 and that blocks the light directly entering from the light projector 58 to the light receiver 59. The region between the light source 50 and the light projector 58 and the region between the light receiver 59 and the grain evaluating unit 60 are entirely configured as an air propagation region where the light propagates in the air.SELECTED DRAWING: Figure 18【課題】光源からの光を貯留状態の穀粒に照射する投光部から、穀粒を透過した光が入射する受光部に対して直接に入射してしまう不都合が低減され、投光部及び受光部の製造コストが抑制される光学式穀粒評価装置を提供する。【解決手段】光源からの光を穀粒に照射する投光部５８と、穀粒を透過した光が入射する受光部５９と、受光した光の情報に基づいて穀粒を評価する穀粒評価部６０と、光源５０と投光部５９との間の領域と、受光部５９と穀粒評価部６０との間の領域とを隔離し、投光部５８から直接に受光部５９に光が入射するのを阻止する遮蔽部ＳＨとを備え、光源５０と投光部５８との間の領域、並びに、受光部５９と穀粒評価部６０との間の領域は、全領域にわたり、光が空気中を伝播する空気伝播領域に構成されている。【選択図】図１８
