There is provided a cell culture device, which includes a plurality of cell culture units, in which the cell culture unit includes: a cell culture tub that defines a culture space for cultivating cells, contains culture medium in the culture unit, and has an air layer above the culture medium; a drainage channel that is connected to the cell culture tub to discharge used culture medium to the integral drainage channel; an open culture medium reservoir that supplies new culture medium into the cell culture tub; and a droplet generator that is disposed between the cell culture tub and the open culture medium reservoir and supplies the culture medium from the open culture medium reservoir to the cell culture tub, using negative pressure of the air layer generated when the used culture medium is discharged.