A bag processing system includes: a conveyance mechanism which includes: a plurality of support devices being able to support and release bags; and a conveyance drive device moving the plurality of support devices intermittently; a liquid introduction device which introduces a liquid into the bags supported by the plurality of support devices; and a conveyance control device which controls the conveyance drive device, wherein: the conveyance drive device moves the plurality of support devices in such a manner that the plurality of support devices exhibit same acceleration-deceleration behavior between each other, and the conveyance control device controls the conveyance drive device to accelerate or decelerate the plurality of support devices in such a manner that shaking of the liquid in the bags is reduced.