PURPOSE: To discriminate unhulled rice and unpolished rice easily by locating photodetectors in the lateral positions with respect to beam directions.

CONSTITUTION: When no grains are supplied, only the respective light axes 7, 8 are supplied to phototransistors (TRs) 5, 6 and the light axis 12 from a light emitting diode 10 is not applied to the TRs 5, 6. When unhulled rice is supplied, the light axes 7, 8, 12 from light emitting diodes 3, 4, 10 respectively do not pass through the unhulled rice and are therefore not detected at all by the TRs 5, 6, thus indicating the supply of the unhulled rice. When unpolished rice is supplied, the unpolished rice is semitransparent and therefore all the light axes 7, 8 from the diodes 3, 4 are detected by the Trs 5, 6 and further the light axis 12 from the diode 10 is refracted in the unpolished rice and is sensed by the TR5, by which the supply of the unpolished rice is detected.