A semiconductor chip manufacturing method includes forming a mask on a surface of a semiconductor wafer, forming an opening on the mask, exposing a dividing region of the semiconductor wafer, a rear surface of the semiconductor wafer is held by a dicing tape via an adhesive layer, singulating the semiconductor wafer into a plurality of semiconductor chips by etching the semiconductor wafer exposed to the opening with a first plasma until the semiconductor wafer reaches a rear surface, removing the mask so that the plurality of element chips from which the mask is removed are held by the holding sheet via the adhesive layer.At the time of removing the mask, the mask is removed from an alkaline developer having a dissolution rate of the mask larger than a dissolution rate of the adhesive layer.