The device has a film-shaped main body part 1, and a predetermined region in the film surface of the main body part has a mesh structure in which a large number of through-holes 20 are arranged. The through-hole has an opening shape having a size allowing smaller cell aggregates to pass through, and the rest of the through-hole is the beam part 30. The beam part is a part that cuts a cell aggregate to be divided, and is integrally connected to form, a network. The cell aggregate can be divided by passing the cell aggregate to be divided through the mesh structure of the device together with the liquid.