PURPOSE: To switch large charging and small charging easily and to weigh grains quickly as specified by providing stages having link mechanisms on the right and left of an oscillating rod in a frame of an inverted T shape, and oscillating the oscillating rod thereby weighing the grains.

CONSTITUTION: A stage 25 is mounted on the right side of an oscillating rod 15 in a frame 2 of an inverted T shape via a pin 13, a vertical rod 11, and a right horizontal weighing table 7. The left side is made into similar construction. A rod 36 is fitted pivotally to the center of the rod 15, and is connected to a weighing lever 29 in the upper part. When grains are admitted into a grain bag 24 on the right side, the table 7 and the rod 11 descend and the rod 15 oscillates downward toward the right, then a switch 22 goes off to change over large charging to small charging so that the large charging is switched to the bag 24 on the left side. Further when the rod 15 moves downward, the upper lever 29 is pulled down by the rod 36, and the grains are weighed with a strain gage. Thus the switching to the large charging and the small charging is easy and the grains are weighed as specified quickly.