PURPOSE: To make the foreign matter of the pebble larger than a grain not to fall from a grain drop port by providing the grain drop port having the gap in which a grain can fall at the terminal side of the guide plate guiding between a grain and spiral groove.

CONSTITUTION: In the device to transfer a grain to a grain moisture measuring instrument and shell cut detector, etc. the spiral groove 1 to transfer a grain by inserting the one piece on the rotary outer periphery of a delivery spiral 2 is formed and the guide plate 3 to guide the grain in the space with the spiral groove 1 thereof is provided close to the outer peripheral face of one side of the spiral groove 1. Also on the terminal part of the delivery spiral 2 the grain fall port 5 having the gap in which the grain can fall between the lower end part 4 of the guide plate 3 and the outer peripheral face of the spiral groove 1 is provided. The grain and smaller impurities than that are guided between the spiral groove 1 and guide plate 3 and transferred to the terminal part and dropped from the fall port 5, but the foreign matter of the pebble, etc. larger than the grain is not dropped from the fall port 5 and discharged to the outside through the discharging path from the terminal of the delivery spiral 2.