The present invention discloses method for manufacturing a wafer stack, in which a wafer back grinding process is performed in a state where wafers are stacked, whereby a wafer stack manufacturing process can be simplified, and manufacturing costs can be reduced. The method for manufacturing a wafer stack, in which a plurality of sub-wafers are stacked on a base wafer, comprises (a) preparing a base wafer having an active layer formed on a front surface thereof and a sub-wafer having an active layer formed on a front surface thereof, and forming a bump on the active layer formed on the base wafer; (b) stacking the sub-wafer on the base wafer such that a front surface of the sub-wafer is directed to the front surface of the base wafer; (c) grinding a rear surface of the sub-wafer to reducethe thickness of the sub-wafer; (d) forming a bump on the rear surface of the sub-wafer; and (e) repeating the steps (b) to (d) at least one time.