PURPOSE: To detect overflowing grains by providing a freely rotating sensing body in the position just under a freely switching shutter.

CONSTITUTION: A shutter 3 in a discharging cylinder part 12 is turned to open a left discharge exit 1. Grains threshed by a threshing machine are supplied into the cylinder part 12 and are stored in a bag through the discharge exit 1. Even if grains strike the inside wall of the discharge cylinder and are scattered irregularly at this time, their transfer to a right discharge exit 2 is stopped by an extending part 3a. When the bag is filled up with grains, grains are overflowed upward and are transferred from a bottom B of a branch part A to the right discharge exit 2. At this time, overflowing grains are stopped by a standing sensing body 5; and when a certain quantity of grains are accumulated, the sensing body 5 is turned and displaced by their weight to rotate a shaft 4 by a prescribed quantity, and a limit switch is turned on to operate an alarm 15, and this state is reported to a worker. The worker operates the shutter 3 reversely by a lever 13a to open the discharge exit 2, and grains are stored in a bag in the side of the discharge exit 2. When the bag is replaced with a fresh bag, press due to grains is released, and the sensing body is restored.