Abstract: A device including a mixing bag for mixing liquids, a cell-suspension bag fluidly connected to the mixing bag, a diluent bag fluidly connected to the mixing bag, and a fluidly connected to the mixing bag is capable of easily preparing a sheet-shaped cell culture without requiring any large-scale equipment. The sheet-shaped cell culture can be aseptically prepared by the device, while reducing the risk of contamination, by using the mixing bag which is fluidically connected to the other bags. The device includes a support having a foldable structure. At least one of the cell-suspension bag, the diluent bag and the filter is fixed to various portions of the support. The device can be folded into a compact size, by folding the various portions of the support, allowing for efficient transportation and storage.