In an unnecessary matter removal method of joining a separation tape onto a semiconductor wafer and, then, separating the separation tape from the semiconductor wafer, thereby separating an unnecessary matter on the semiconductor wafer together with the separation tape, the separation tape is separated from the semiconductor wafer in such a manner that an edge member is brought into contact with the separation tape joined to the semiconductor wafer, and a tip end of the edge member is pressed to the semiconductor wafer at a separation completion end portion where the unnecessary matter is separated from the wafer.