To enable switching over of a grain bag to a bag for male workers of normal physical power, and a bag for women and not strong male worker by a simple operation so as to be easily handled by anyone by changing and regulating the capacity by opening/closing a fastener provided at a prescribed part on an inside peripheral part of the bag.

An unhulled rice bag A is provided with two fasteners 12 along the distal direction of a bag on right and left peripheral parts in the bag, and the capacity of the bag can be changed and regulated by opening/closing the fasteners 12. For a general male worker, the fastener 12 is opened to handle the bag of the capacity of 30 kg with unhulled rice, while for a female worker, or a weak male worker, the capacity of the bag is reduced to 20 kg of unhulled rice if only the left fastener 12, for example, is closed. If only the right fastener 12 is closed, the capacity becomes 25 kg, and if both fasteners 12 are closed, the capacity becomes 15 kg. Troublesome operation to select the bag according to the kind of the grain bag can be avoided, and the bag can be handled by anyone.